1 00:00:00,066 --> 00:00:03,636 This is a 2021 Toyota Sienna. 2 00:00:03,670 --> 00:00:04,971 It's a minivan. 3 00:00:05,038 --> 00:00:07,540 The best kind of three row vehicle out there, 4 00:00:07,540 --> 00:00:11,244 according to everyone who can get over themselves. 5 00:00:11,244 --> 00:00:12,345 For this model year, 6 00:00:12,345 --> 00:00:14,748 Toyota did something very daring. 7 00:00:14,814 --> 00:00:18,785 They dropped the V6 engine and made every single one of these 8 00:00:18,818 --> 00:00:20,754 a hybrid electric vehicle. 9 00:00:21,121 --> 00:00:22,389 In doing so, 10 00:00:22,422 --> 00:00:26,626 Toyota ruffled more than a few feathers, but they also released a minivan 11 00:00:26,626 --> 00:00:29,229 which could go more than 50% farther 12 00:00:29,229 --> 00:00:32,899 on every gallon of gasoline it burns than its competition. 13 00:00:33,299 --> 00:00:36,302 This thing has gotten a shockingly consistent 14 00:00:36,302 --> 00:00:39,939 34 miles per gallon over its life, city or highway. 15 00:00:40,473 --> 00:00:42,442 And it's a minivan. 16 00:00:42,475 --> 00:00:45,879 My first car, a Honda Civic, could barely squeeze 17 00:00:45,879 --> 00:00:49,549 that out on the highway and got far worse fuel economy in the city. 18 00:00:49,549 --> 00:00:52,052 And that thing was a small two door coupe. 19 00:00:52,352 --> 00:00:54,721 This is a three row minivan. 20 00:00:54,821 --> 00:00:56,322 It's even all wheel drive. 21 00:00:56,356 --> 00:00:57,924 The thing’s quite impressive. 22 00:00:58,324 --> 00:01:04,697 By now, most people know that hybrid cars get better fuel economy than their non-electrified counterparts 23 00:01:04,697 --> 00:01:09,035 through the use of a battery pack which stores electrical energy and electric motors 24 00:01:09,035 --> 00:01:11,805 which use that energy to assist the engine. 25 00:01:12,105 --> 00:01:15,241 But to explain this video's title, 26 00:01:15,475 --> 00:01:20,547 something which I think is less well understood, is that those batteries and motors 27 00:01:20,580 --> 00:01:27,787 actually have relatively little to do with how hybrid cars attain their amazing fuel economy numbers. 28 00:01:28,455 --> 00:01:33,860 See, this vehicle is not one of those newfangled plug-in hybrids. 29 00:01:33,960 --> 00:01:37,397 It's a conventional hybrid like the original Toyota Prius. 30 00:01:37,430 --> 00:01:41,835 And that means all of the energy available to its drivetrain 31 00:01:41,835 --> 00:01:44,404 comes from the gasoline in its fuel tank. 32 00:01:44,704 --> 00:01:48,174 There is no way to charge its batteries except driving it. 33 00:01:48,208 --> 00:01:53,179 And that means all of the energy the hybrid system uses to make the car go? 34 00:01:53,713 --> 00:01:56,683 It ultimately came from the gasoline and the engine. 35 00:01:57,217 --> 00:02:01,721 So why does it even have those electric motors and batteries? 36 00:02:02,322 --> 00:02:05,158 Well, because without them, driving this thing would suuuuccccck. 37 00:02:05,158 --> 00:02:09,529 To explain, we need to back up a bit. 38 00:02:09,596 --> 00:02:12,732 I wasn't intending on making this video yet. 39 00:02:12,732 --> 00:02:16,669 I'm in the middle of a series on engine management technology, and so far 40 00:02:16,669 --> 00:02:18,705 I've only covered the catalytic converter 41 00:02:18,705 --> 00:02:22,275 and a mechanical overview of the internal combustion engine. 42 00:02:22,342 --> 00:02:27,080 So skipping ahead to hybrid drivetrains sure is skipping a lot. 43 00:02:27,113 --> 00:02:33,520 But you see, my spidey senses keep picking up on frankly wild misunderstandings 44 00:02:33,520 --> 00:02:39,192 about hybrid cars and how they work, and also why they work the way they do. 45 00:02:39,792 --> 00:02:42,896 Now that suddenly people care about fuel economy again, 46 00:02:42,929 --> 00:02:46,232 I figured it would be worth providing some actual information 47 00:02:46,232 --> 00:02:49,035 and not just a collection of hot takes. 48 00:02:49,235 --> 00:02:52,105 For example, if you've been under the impression 49 00:02:52,105 --> 00:02:54,908 that a car like this has two separate drivetrains, 50 00:02:54,941 --> 00:03:01,414 an electric one and a gasoline one that have been Frankensteined together into a wildly complex contraption, 51 00:03:01,447 --> 00:03:03,583 that's simply not true. 52 00:03:04,150 --> 00:03:07,320 What Toyota's hybrid system does is replace 53 00:03:07,320 --> 00:03:11,758 the traditional transmission with a new device, which is in fact much, 54 00:03:11,858 --> 00:03:18,298 much simpler than even the six speed manual gearbox you'll find in this Nissan cube. 55 00:03:19,232 --> 00:03:20,466 Let me say that again. 56 00:03:20,500 --> 00:03:26,973 This thing's drivetrain is simpler than a conventional manual transmission, and in fact, 57 00:03:26,973 --> 00:03:29,375 it isn't even really a transmission at all. 58 00:03:30,176 --> 00:03:31,711 But I'll get back to that. 59 00:03:31,744 --> 00:03:36,149 The reason hybrid drivetrains were developed is that, frankly, 60 00:03:36,249 --> 00:03:42,555 the internal combustion engine is just not very good at what it's supposed to do. 61 00:03:42,889 --> 00:03:48,995 Yes, these are very interesting devices which tickle the ‘tisms and make lots of very satisfying noises. 62 00:03:48,995 --> 00:03:52,432 But when you boil them down to their core job, 63 00:03:52,465 --> 00:03:57,503 turning the chemical energy in a fuel into mechanical energy to move a car, 64 00:03:58,137 --> 00:03:59,806 they're quite terrible. 65 00:04:00,039 --> 00:04:06,779 You are lucky to capture just one quarter of the energy contained in gasoline using an engine, 66 00:04:06,779 --> 00:04:09,349 and the rest will just be wasted as heat. 67 00:04:09,582 --> 00:04:12,352 That's why your car's got such a big radiator, 68 00:04:12,352 --> 00:04:16,022 and why cooling system problems can quickly destroy an engine. 69 00:04:16,422 --> 00:04:18,558 But what I'd like to explain today 70 00:04:18,558 --> 00:04:23,463 is that part of the reason engines are like that is due to a compromise. 71 00:04:24,230 --> 00:04:27,900 You see, engines produce wildly different amounts of power 72 00:04:27,900 --> 00:04:30,536 depending on how fast they're going. 73 00:04:30,536 --> 00:04:35,341 Each combustion event which occurs in the cylinders can only produce so much power. 74 00:04:35,341 --> 00:04:38,111 So when you need to produce more engine power, 75 00:04:38,244 --> 00:04:40,913 you need those events to happen more frequently 76 00:04:40,913 --> 00:04:43,449 which means you need the engine to speed up. 77 00:04:43,683 --> 00:04:51,124 For example, this MR-18DE found in the Nissan Cube can only produce its rated 122 horsepower 78 00:04:51,124 --> 00:04:55,295 when the crankshaft is spinning at about 5,200 RPM: 79 00:04:55,495 --> 00:04:58,031 not that far from engine redline. 80 00:04:58,164 --> 00:05:00,867 At any slower engine speed, 81 00:05:00,867 --> 00:05:03,870 it cannot produce full power, and in fact, 82 00:05:03,870 --> 00:05:06,105 when running at normal cruising speeds, 83 00:05:06,139 --> 00:05:08,775 this thing can barely put out 50 horsepower. 84 00:05:09,309 --> 00:05:12,011 That is why your car has a transmission. 85 00:05:12,145 --> 00:05:17,183 We need to be able to vary the ratio between how quickly the engine crankshaft is spinning 86 00:05:17,183 --> 00:05:23,389 and how quickly the wheels are spinning in order to make practical use of an engine given its operating characteristics. 87 00:05:23,856 --> 00:05:27,994 When accelerating, we want to allow the engine to rev up fast 88 00:05:27,994 --> 00:05:30,830 so it can produce more power to get the car moving, 89 00:05:30,897 --> 00:05:33,333 which is why we have low gear ratios. 90 00:05:33,533 --> 00:05:42,141 But as the car speeds up, the wheels will start spinning too fast for the engine to keep up and that would limit how fast the car can go. 91 00:05:42,308 --> 00:05:47,480 But with a transmission, we can change the gear ratio as we accelerate 92 00:05:47,480 --> 00:05:52,819 which will slow the engine back down while keeping the wheels moving as quickly as they were before. 93 00:05:53,019 --> 00:05:56,622 It's the exact same principle as the different gears on a bicycle. 94 00:05:57,290 --> 00:06:01,260 But we don't just want those gears to unlock the engine's power. 95 00:06:01,294 --> 00:06:04,931 In general, internal combustion engines are more fuel efficient 96 00:06:04,931 --> 00:06:07,166 when they are running at lower speeds. 97 00:06:07,533 --> 00:06:11,137 There are many reasons for this which aren't worth picking apart too much, 98 00:06:11,137 --> 00:06:17,009 but remember that an engine is full of metal parts sliding against each other very quickly. 99 00:06:17,243 --> 00:06:20,880 While the lubrication system will do its best to reduce friction, 100 00:06:20,913 --> 00:06:26,419 there's still lots of it working to slow the engine down and generate heat as it runs. 101 00:06:26,419 --> 00:06:30,656 And the faster the engine spins, the more friction there is. 102 00:06:30,957 --> 00:06:35,695 There are also plenty of pumping losses which get worse as engine speed increases. 103 00:06:35,695 --> 00:06:38,331 But again, it's not worth dwelling on this. 104 00:06:38,498 --> 00:06:40,933 What's important is that ideally, 105 00:06:40,933 --> 00:06:46,873 we want an engine which can spin quickly when we need it to produce lots of power to accelerate, 106 00:06:46,873 --> 00:06:52,445 but which operates very efficiently at lower speeds for fuel efficient cruising. 107 00:06:53,212 --> 00:06:54,814 But here's the problem: 108 00:06:55,415 --> 00:06:58,251 Life is cruel, and we can't have that. 109 00:06:58,618 --> 00:07:03,055 The best we can manage is a pretty major compromise named Otto. 110 00:07:03,656 --> 00:07:06,159 When discussing the four stroke engine cycle, 111 00:07:06,192 --> 00:07:09,996 we are in fact almost universally discussing the Otto cycle. 112 00:07:10,029 --> 00:07:13,966 That's O - T - T - O, named for my man Nick over here. 113 00:07:14,233 --> 00:07:15,234 Quick recap: 114 00:07:15,234 --> 00:07:19,071 The reciprocating pistons work in conjunction with intake and exhaust valves. 115 00:07:19,105 --> 00:07:22,809 During the intake stroke, the piston is descending and the intake valve is open, 116 00:07:22,809 --> 00:07:25,812 resulting in an air fuel mixture being drawn into the cylinder. 117 00:07:25,812 --> 00:07:27,180 When the piston is at the bottom, 118 00:07:27,180 --> 00:07:30,049 the intake valve closes and the cylinder is then sealed. 119 00:07:30,116 --> 00:07:34,253 The air fuel mixture will then be compressed as the piston travels up back towards the top, 120 00:07:34,253 --> 00:07:37,256 and when it's near the top, the spark plug fires, 121 00:07:37,256 --> 00:07:43,396 and the conflagration of hot expanding gases forces the piston back down into the engine block producing engine power, 122 00:07:43,429 --> 00:07:50,036 after which the exhaust valve will open to allow the piston to push those spent gases out of the chamber as it comes back up, 123 00:07:50,036 --> 00:07:51,771 so the process can repeat. 124 00:07:52,071 --> 00:07:53,039 Cool. 125 00:07:53,039 --> 00:07:58,911 And the Otto cycle does a decent job of making an engine powerful when it needs to be, 126 00:07:58,911 --> 00:08:02,615 and also reasonably efficient when under moderate load. 127 00:08:02,915 --> 00:08:06,719 This is why the Otto cycle engine is what gets put in cars. 128 00:08:06,752 --> 00:08:10,156 It's a decent compromise between power and efficiency, 129 00:08:10,156 --> 00:08:14,093 and meets the varying needs of an automobile reasonably well. 130 00:08:14,894 --> 00:08:19,632 But then this guy named James Atkinson realized that since the power 131 00:08:19,665 --> 00:08:23,636 the engine produces comes from the expansion of hot gases, 132 00:08:23,736 --> 00:08:29,542 the Otto cycle wastes a bit of energy by constraining how much those gases can expand. 133 00:08:30,309 --> 00:08:32,111 See, in the Otto cycle, 134 00:08:32,144 --> 00:08:37,617 the length of the intake and compression strokes are identical to the power stroke. 135 00:08:37,950 --> 00:08:43,222 Since the volume of gas after combustion is much greater than before ignition, 136 00:08:43,356 --> 00:08:45,558 Atkinson saw this as a problem. 137 00:08:45,825 --> 00:08:50,196 He figured at the end of the power stroke, when the piston is back at the bottom, 138 00:08:50,196 --> 00:08:55,268 the newly expanded hot gases are still exerting pressure on the piston. 139 00:08:55,701 --> 00:08:58,871 That could be captured, but in the Otto cycle, 140 00:08:58,905 --> 00:09:03,309 the exhaust valve will open at that point, relieving the pressure inside the cylinder 141 00:09:03,309 --> 00:09:05,945 and preventing us from harnessing that energy. 142 00:09:06,612 --> 00:09:08,948 Atkinson got pretty hot and bothered by this, 143 00:09:08,948 --> 00:09:11,951 so he designed... this contraption. 144 00:09:12,385 --> 00:09:17,089 If this looks familiar, you've probably spent some time taking the green stairs. 145 00:09:17,089 --> 00:09:21,827 Engines of the 19th century were all sorts of different from how we imagine them today. 146 00:09:21,827 --> 00:09:26,766 And Atkinson used two opposing pistons in the same combustion cylinder, 147 00:09:26,766 --> 00:09:29,435 which were being driven by an external crankshaft 148 00:09:29,435 --> 00:09:34,774 and some totally normal linkages to make them move like that. 149 00:09:35,508 --> 00:09:38,811 Yeah, this thing is quite strange and perhaps a little difficult to follow, 150 00:09:38,811 --> 00:09:41,614 even with this lovely animation by Michael Frey. 151 00:09:42,014 --> 00:09:45,918 But the key thing to notice is that the distance between the two pistons 152 00:09:45,952 --> 00:09:48,921 varies dramatically throughout a full cycle. 153 00:09:49,488 --> 00:09:53,526 This effectively enlarges the combustion chamber during the power stroke, 154 00:09:53,526 --> 00:09:59,031 which in turn allows the expanding gases to do more work before they're tossed out of the cylinder. 155 00:09:59,532 --> 00:10:04,003 Atkinson would later redesign his engine to be slightly less steampunk, 156 00:10:04,003 --> 00:10:06,272 but still extremely weird. 157 00:10:06,839 --> 00:10:09,108 We sure did love linkages back in the day, huh? 158 00:10:09,542 --> 00:10:13,312 But in this design, you can see the point a little more clearly. 159 00:10:13,579 --> 00:10:18,150 The piston hardly moves at all in the intake and compression strokes, 160 00:10:18,150 --> 00:10:21,253 but it moves much farther during the power stroke, 161 00:10:21,320 --> 00:10:25,057 allowing those hot gases to perform more work on the piston. 162 00:10:25,858 --> 00:10:27,860 Now, back in 1887, 163 00:10:27,860 --> 00:10:30,896 we didn't have the same valve technology we do now, 164 00:10:30,896 --> 00:10:33,799 so this contraption made more sense in the past. 165 00:10:33,799 --> 00:10:37,236 But today we can accomplish more or less the same thing 166 00:10:37,236 --> 00:10:40,106 with a conventional Otto cycle engine design 167 00:10:40,139 --> 00:10:43,309 simply through messing with the intake valve timing. 168 00:10:43,709 --> 00:10:48,948 If we allow the intake valve to remain open through part of the compression stroke, 169 00:10:48,981 --> 00:10:52,718 the ascending piston will force some of the air fuel mixture 170 00:10:52,752 --> 00:10:59,225 out of the cylinder and back into the intake manifold before the cylinder is sealed for compression. 171 00:10:59,659 --> 00:11:04,063 When done this way, it's known as a modified Atkinson cycle engine, 172 00:11:04,063 --> 00:11:09,669 and that's what you'll find in any decent hybrid vehicle going back to the original Toyota Prius. 173 00:11:10,269 --> 00:11:14,240 Leaving the intake valves open as the piston begins to ascend 174 00:11:14,373 --> 00:11:19,945 means we can effectively shrink the size of the combustion chamber during the compression stroke 175 00:11:19,945 --> 00:11:25,384 and enlarge it during the power stroke, attaining the same effect that Atkinson did 176 00:11:25,418 --> 00:11:27,453 with all those wild linkages. 177 00:11:27,887 --> 00:11:29,021 The result? 178 00:11:29,255 --> 00:11:37,129 A modified Atkinson cycle engine can get over 40% of the chemical energy in gasoline converted to mechanical energy. 179 00:11:37,563 --> 00:11:43,869 Toyota claims the 2.5l engine in this Toyota Sienna can hit 41% thermal efficiency. 180 00:11:44,370 --> 00:11:49,108 I've also seen some spec sheets claim this engine tops out at 39.8%, 181 00:11:49,108 --> 00:11:50,976 so it might not quite hit 40. 182 00:11:50,976 --> 00:11:53,446 But either way, it's quite good. 183 00:11:54,080 --> 00:11:56,015 For an engine: no matter what you do, 184 00:11:56,015 --> 00:11:59,485 the internal combustion engine remains not that great at its job, 185 00:11:59,485 --> 00:12:05,925 but the Atkinson cycle is a substantial efficiency improvement over a standard Otto cycle engine. 186 00:12:06,425 --> 00:12:13,799 So if all it takes to make an engine significantly more fuel efficient is to tweak the intake valve timing, 187 00:12:14,200 --> 00:12:20,172 well, you might wonder why we aren't putting modified Atkinson cycle engines into every car on the road. 188 00:12:21,207 --> 00:12:24,376 Well, with the advent of variable valve timing, 189 00:12:24,376 --> 00:12:26,879 we kind of are a little bit. 190 00:12:26,912 --> 00:12:29,882 But when it comes to the engine itself, 191 00:12:29,949 --> 00:12:32,685 you still have to make design compromises. 192 00:12:33,119 --> 00:12:35,087 Remember, we're expecting this thing 193 00:12:35,121 --> 00:12:38,257 to move the car from a stop and accelerate quickly. 194 00:12:38,390 --> 00:12:42,361 Yet we also want it to run efficiently when at cruising speed. 195 00:12:42,628 --> 00:12:47,433 And whenever you try to optimize for one of those two things, 196 00:12:47,600 --> 00:12:49,802 you make the other one worse. 197 00:12:50,336 --> 00:12:52,538 This is the crux of the problem. 198 00:12:52,571 --> 00:12:56,909 The Atkinson cycle maximizes fuel efficiency at cruising speeds, 199 00:12:57,343 --> 00:13:02,081 but it's pretty lousy at delivering large amounts of power when you need it. 200 00:13:02,414 --> 00:13:06,218 And, well, that kind of lousy engine 201 00:13:06,218 --> 00:13:09,755 is exactly what's sitting in this van’s engine compartment. 202 00:13:09,855 --> 00:13:15,094 While this 2.5l four cylinder can produce 186 horsepower... 203 00:13:15,494 --> 00:13:20,699 well, first of all, that's not a lot for a vehicle this large or an engine that large. 204 00:13:20,699 --> 00:13:24,236 But also the engine delivers power in a way 205 00:13:24,236 --> 00:13:27,373 which many people would find incredibly annoying. 206 00:13:27,406 --> 00:13:30,943 So if all this minivan had was that engine, 207 00:13:30,943 --> 00:13:35,815 it would be a very slow turd which nobody would enjoy driving. 208 00:13:35,815 --> 00:13:38,984 It would be very fuel efficient! 209 00:13:38,984 --> 00:13:40,986 In fact, with the right transmission 210 00:13:41,020 --> 00:13:43,622 not far off from what this thing can manage, 211 00:13:43,622 --> 00:13:47,960 but it would be an unacceptable driving experience for most people. 212 00:13:48,227 --> 00:13:55,301 This engine is extremely compromised by being designed for fuel efficiency above all else. 213 00:13:56,268 --> 00:14:00,606 However, the van doesn't just have that engine. 214 00:14:00,606 --> 00:14:04,743 And that, dear viewer, is the point of hybrid cars. 215 00:14:05,010 --> 00:14:07,179 See, here's the thing about cars. 216 00:14:07,246 --> 00:14:11,183 They only need large amounts of engine power to accelerate. 217 00:14:11,483 --> 00:14:17,423 Sure, having 300 horses under the hood can make car go vroom real fast, but once you're up to speed, 218 00:14:17,456 --> 00:14:20,826 you don't need any where near that much power. 219 00:14:21,227 --> 00:14:26,165 This minivan only needs about 30 horsepower to maintain 70 miles an hour. 220 00:14:26,432 --> 00:14:29,034 You can get that out of some lawnmowers. 221 00:14:29,034 --> 00:14:35,641 So rather than give the car a huge V6 engine just to make highway on-ramps a little easier, 222 00:14:36,542 --> 00:14:41,447 what if we gave it a little four banger optimized for amazing efficiency at cruising speeds, 223 00:14:41,447 --> 00:14:46,218 and we used some electric motors to give the engine a boost when accelerating? 224 00:14:46,585 --> 00:14:50,756 We can power those motors using some stored energy in a small battery pack, 225 00:14:50,756 --> 00:14:55,127 and then, whenever we get a chance, we'll recharge what we took from the batteries 226 00:14:55,127 --> 00:14:58,998 and we'll get them ready for the next time you need to pass someone or whatever. 227 00:14:59,498 --> 00:15:03,402 That's really what hybrid drivetrains have always been about. 228 00:15:03,435 --> 00:15:08,140 They’re an exercise in solving the edge case of rapid acceleration 229 00:15:08,140 --> 00:15:14,313 without resorting to the brute force option of equipping a car with a bigger, thirstier engine. 230 00:15:14,780 --> 00:15:17,483 The electric motors and battery pack in this thing 231 00:15:17,483 --> 00:15:20,719 are only there to be an auxiliary source of energy 232 00:15:20,719 --> 00:15:24,723 which can be borrowed from and replenished whenever it makes sense to do so. 233 00:15:25,190 --> 00:15:29,228 Sometimes that will be for increasing total system power output. 234 00:15:29,261 --> 00:15:33,799 While the engine in this minivan tops out at 186 horsepower, 235 00:15:33,799 --> 00:15:38,003 its electric motors can add about 60 horsepower on top of that, 236 00:15:38,037 --> 00:15:42,341 bringing the total to 245 horsepower whenever you floor it. 237 00:15:42,408 --> 00:15:49,315 Incidentally, that's five horsepower more than the 3.5l V6 in a 2002 Honda Odyssey, 238 00:15:49,381 --> 00:15:53,052 a minivan which could barely manage 20 miles per gallon. 239 00:15:53,285 --> 00:15:56,588 But the drivetrain in this van will also borrow energy 240 00:15:56,588 --> 00:16:00,426 from the battery pack during mild acceleration, if it makes sense. 241 00:16:00,526 --> 00:16:05,364 For instance, if the throttle pedal is pushed down enough to request 80 horsepower, 242 00:16:05,364 --> 00:16:11,804 but the car's computers know that the engine is more fuel efficient when limited to 60 horsepower or less... 243 00:16:12,571 --> 00:16:16,175 well, then the car is just going to have the engine produce 60 horsepower 244 00:16:16,175 --> 00:16:21,280 and fill in the remaining 20 using the electric motors and energy stored in the battery pack. 245 00:16:21,914 --> 00:16:26,418 Now here's where I need to take a break and explain what I meant by the video title. 246 00:16:26,952 --> 00:16:29,621 Obviously, “nobody” is hyperbole. 247 00:16:29,655 --> 00:16:34,026 The engineers designing these things sure do get the point of hybrid cars! 248 00:16:34,026 --> 00:16:40,265 But when the broader public discusses how hybrid cars attain their better fuel economy, 249 00:16:40,332 --> 00:16:45,304 discussions tend to focus on the cool new stuff a hybrid drivetrain can unlock, 250 00:16:45,304 --> 00:16:50,309 like regenerative braking or the ability to move the car without using the engine. 251 00:16:50,709 --> 00:16:53,178 But what I'm trying to get across here 252 00:16:53,178 --> 00:16:55,981 is that that's all just icing on the cake. 253 00:16:56,115 --> 00:16:59,218 The actual cake batter is the engine. 254 00:16:59,718 --> 00:17:02,621 Yes, hybrid cars need those electric motors 255 00:17:02,621 --> 00:17:08,394 to make the engine not seem like the wheezy, compromised slow turd of a thing that it is, 256 00:17:08,394 --> 00:17:12,297 but that engine is the only thing which consumes energy. 257 00:17:12,297 --> 00:17:15,234 And that's why it's the special sauce. 258 00:17:15,734 --> 00:17:19,138 Since James Atkinson died in 1914, 259 00:17:19,171 --> 00:17:22,941 we could have had this special sauce in cars the whole time. 260 00:17:22,941 --> 00:17:26,612 But the engine on its own is miserable. 261 00:17:26,612 --> 00:17:29,114 And until we had perfected the electronics 262 00:17:29,114 --> 00:17:32,918 and control systems necessary to develop hybrid drivetrains, 263 00:17:33,052 --> 00:17:36,555 nobody was going to buy a car with an Atkinson cycle engine. 264 00:17:36,789 --> 00:17:38,357 Not even a midwesterner. 265 00:17:38,857 --> 00:17:45,064 But even though an Atkinson-cycle engine is much more fuel efficient than an Otto cycle engine, 266 00:17:45,297 --> 00:17:49,902 it is still a reciprocating piston engine with many of the same problems. 267 00:17:49,935 --> 00:17:53,338 This engine still has friction losses and pumping losses, 268 00:17:53,372 --> 00:17:57,976 meaning it's only at its peak fuel efficiency under certain conditions. 269 00:17:58,010 --> 00:18:04,550 So the other thing we can do with a hybrid drivetrain is keep the engine in those conditions 270 00:18:04,550 --> 00:18:11,623 under many more circumstances than would be possible without some batteries and motors to fill in usability gaps. 271 00:18:12,324 --> 00:18:16,428 And now here's the other thing I meant by the video title. 272 00:18:16,662 --> 00:18:22,734 If you're not familiar with how Toyota's hybrid system works both mechanically and operationally, 273 00:18:23,702 --> 00:18:29,174 you should probably hold off on writing that comment explaining how you think hybrid cars could be improved. 274 00:18:29,174 --> 00:18:32,811 Because I promise you, Toyota is already doing that. 275 00:18:32,911 --> 00:18:35,247 Okay, I've got a lot to unpack here. 276 00:18:35,514 --> 00:18:38,684 First, I don't mean to sound like a shill for Toyota. 277 00:18:38,684 --> 00:18:42,788 For one thing, they've really been dragging their feet on battery electric vehicles 278 00:18:42,788 --> 00:18:45,591 and are still playing with hydrogen for some reason. 279 00:18:45,591 --> 00:18:48,093 So, you know, there's that. 280 00:18:48,093 --> 00:18:52,498 Also, their user interface software is... well, it could be better. 281 00:18:52,498 --> 00:18:56,401 But when it comes to the engineering of hybrid drivetrains 282 00:18:57,202 --> 00:18:59,037 they kind of nailed it. 283 00:18:59,104 --> 00:19:01,507 There's a reason they are the standard bearer 284 00:19:01,507 --> 00:19:03,542 and they've earned that distinction. 285 00:19:03,642 --> 00:19:08,280 But before I explain the mechanical parts of their Hybrid Synergy Drive 286 00:19:08,280 --> 00:19:12,551 and dispel some of the various misconceptions about hybrid cars that are out there, 287 00:19:13,418 --> 00:19:16,688 let's first look at what the thing is actually doing as you drive it. 288 00:19:16,688 --> 00:19:18,790 And with the help of this scan tool, 289 00:19:18,790 --> 00:19:21,927 I can graph some parameters which will help us make sense of it. 290 00:19:22,194 --> 00:19:26,131 We begin our journey at a gas station in Hammond, Indiana. 291 00:19:26,165 --> 00:19:32,070 I've set the scan tool up to log vehicle speed in blue, engine RPM in red, 292 00:19:32,137 --> 00:19:37,176 the accelerator pedal position in black, and the hybrid battery state of charge in green. 293 00:19:37,409 --> 00:19:41,580 Not graphed, but shown below is the target engine power in Watts. 294 00:19:41,580 --> 00:19:44,616 And for those who would like to convert that to horsepower, 295 00:19:44,650 --> 00:19:47,286 divide that number by 746. 296 00:19:47,686 --> 00:19:49,254 Before we get on the road, 297 00:19:49,254 --> 00:19:54,259 I'm going to take the car through a car wash, and I want you to notice that the car does not need 298 00:19:54,259 --> 00:19:56,595 the engine to be running in order to move. 299 00:19:56,828 --> 00:19:59,965 Right now, it's simply using one of its two electric motors 300 00:19:59,965 --> 00:20:02,701 to spin the front wheels and drag itself along. 301 00:20:03,068 --> 00:20:08,473 When I started logging, the hybrid battery was at 52.5% state of charge, 302 00:20:08,473 --> 00:20:10,976 and by the time I had parked it in the car wash, 303 00:20:10,976 --> 00:20:13,212 it was down to 49%. 304 00:20:13,612 --> 00:20:15,981 Now the car is on this whole time. 305 00:20:16,315 --> 00:20:19,351 The reason the battery state of charge is slowly dropping 306 00:20:19,351 --> 00:20:21,987 is because the car has a lot of electronics running, 307 00:20:21,987 --> 00:20:26,825 including the HVAC system which has an electric air conditioning compressor. 308 00:20:27,192 --> 00:20:33,632 That's one of the fun side benefits of having a hybrid drivetrain with a lot of stored electrical energy on board: 309 00:20:33,699 --> 00:20:36,401 if you make all the accessories electric, 310 00:20:36,435 --> 00:20:40,005 the car can be fully functional while the engine is shut down. 311 00:20:40,739 --> 00:20:44,509 The car let the state of charge get down to just below 40%, 312 00:20:44,509 --> 00:20:47,045 and then it decided to start the engine. 313 00:20:47,179 --> 00:20:50,749 This happened just before the end of the car wash. 314 00:20:50,882 --> 00:20:57,422 But I want you to notice as I pull out that it's not really working to charge the battery. 315 00:20:57,456 --> 00:21:02,628 Instead it simply maintaining its state of charge around 39%. 316 00:21:03,195 --> 00:21:07,032 I will explain why it's not charging the battery in due time. 317 00:21:07,032 --> 00:21:08,667 But now that I'm actually moving, 318 00:21:08,667 --> 00:21:13,839 I want you to notice that the engine speed is entirely decoupled from the vehicle speed. 319 00:21:14,106 --> 00:21:17,676 This cars engine can be used as an electrical generator, 320 00:21:17,676 --> 00:21:20,245 to push the car forward with the front wheels, 321 00:21:20,245 --> 00:21:26,885 or indeed both at the same time, which is actually the only way the engine can push the car forward. 322 00:21:26,918 --> 00:21:28,520 But more on that later. 323 00:21:28,787 --> 00:21:31,156 As I accelerate to this traffic light, 324 00:21:31,189 --> 00:21:35,027 you'll see the engine speed up to produce more power to accelerate. 325 00:21:35,027 --> 00:21:40,999 But then the light was turning red and I had to let off the gas so the engine revved right back down. 326 00:21:40,999 --> 00:21:45,637 And notice that here the battery state of charge went up rapidly, 327 00:21:45,637 --> 00:21:49,207 but only as vehicle speed was decreasing. 328 00:21:49,474 --> 00:21:54,446 That's because the car was using regenerative braking to charge the battery pack. 329 00:21:55,180 --> 00:21:57,182 Again, I'll explain that more later. 330 00:21:57,182 --> 00:22:00,652 But now the light turning red was a problem for me 331 00:22:00,652 --> 00:22:05,357 because I need to take that entrance ramp up there and I'm in the wrong lane. 332 00:22:05,424 --> 00:22:08,994 So I had to practically floor it to get around this truck next to me, 333 00:22:08,994 --> 00:22:10,595 and I felt very bad about that maneuver. 334 00:22:10,595 --> 00:22:13,231 But look at the data we got out of it! 335 00:22:13,332 --> 00:22:18,437 Here we see the hybrid battery state of charge quickly drop back below 40% 336 00:22:18,437 --> 00:22:24,343 as the car used some of its stored energy to assist the engine during this sudden need for power. 337 00:22:24,843 --> 00:22:27,512 But as soon as I let off the accelerator, 338 00:22:27,579 --> 00:22:29,881 the state of charge stopped dropping. 339 00:22:30,182 --> 00:22:34,553 I was nowhere near highway speeds yet and still had to do quite a lot more accelerating. 340 00:22:34,553 --> 00:22:38,924 But now I don't need to exceed what the engine can do by itself. 341 00:22:38,957 --> 00:22:42,627 So the car simply lets the engine do all the work. 342 00:22:42,694 --> 00:22:47,099 In fact, the hybrid battery state of charge is increasing slightly, 343 00:22:47,099 --> 00:22:49,835 indicating that the engine is producing more power 344 00:22:49,835 --> 00:22:53,071 than is actually required to move the car right now, and it's 345 00:22:53,071 --> 00:22:56,241 using that excess power to charge the battery back up. 346 00:22:56,675 --> 00:23:00,078 Now here's something which is very important. 347 00:23:00,245 --> 00:23:03,048 It is unusual that this is happening 348 00:23:03,048 --> 00:23:07,285 and the car doesn't ever want to do this if it can be avoided. 349 00:23:07,519 --> 00:23:11,356 It's only using the engine to charge the battery pack right now 350 00:23:11,356 --> 00:23:19,297 because the battery fell below 45% state of charge from the car sitting in the car wash parked for a good five minutes. 351 00:23:19,898 --> 00:23:25,404 45% is as low as the car ever wants the battery to be when it's being driven, 352 00:23:25,437 --> 00:23:28,173 because if it's lower than that, the car 353 00:23:28,206 --> 00:23:33,245 can't sustain the power boost function of its electric motors for very long at all. 354 00:23:33,912 --> 00:23:39,785 When getting around that truck, we saw it lose three percentage points in just six seconds 355 00:23:39,785 --> 00:23:41,420 and I wasn't even flooring it. 356 00:23:41,686 --> 00:23:45,857 So now that the car is in drive and in motion, 357 00:23:45,857 --> 00:23:53,498 it wants to quickly get the battery back to its target minimum charge to prevent an apparent loss of available power to the driver. 358 00:23:54,032 --> 00:23:59,404 But, and this is something I really want to make sure everyone out there understands, 359 00:23:59,438 --> 00:24:01,973 in all other circumstances, 360 00:24:01,973 --> 00:24:09,815 the car goes out of its way to avoid charging the battery pack using the engine, and for a very good reason. 361 00:24:10,315 --> 00:24:13,418 If you'll permit me, one of the things I'd like to unpack 362 00:24:13,418 --> 00:24:17,255 is what I have found to be a very common, but I would argue 363 00:24:17,322 --> 00:24:21,860 misplaced fixation on the concept of the diesel-electric locomotive 364 00:24:21,860 --> 00:24:26,465 and how that technology could potentially be deployed in hybrid cars like this. 365 00:24:26,898 --> 00:24:30,802 I'm not going to get too deep into this, because what follows will hopefully explain why 366 00:24:30,802 --> 00:24:33,839 I believe the fixation is very misplaced. 367 00:24:33,839 --> 00:24:37,909 But one of my goals with this video is to help more people realize 368 00:24:37,909 --> 00:24:45,116 that it is not good to convert one source of energy to another unless you actually need to do that. 369 00:24:45,383 --> 00:24:47,285 Now, I know this might sound odd 370 00:24:47,319 --> 00:24:52,023 to the many people out there who know that a diesel-electric locomotive does just that: 371 00:24:52,057 --> 00:24:57,796 They use a generator to convert the mechanical output from their diesel engine into electricity, 372 00:24:57,796 --> 00:25:00,999 which will then power electric motors to move the train. 373 00:25:01,566 --> 00:25:04,069 But what I've never seen discussed 374 00:25:04,069 --> 00:25:08,206 is that efficiency is not the point of that process. 375 00:25:08,206 --> 00:25:13,345 And in fact, trains would be more fuel efficient if they weren't doing that. 376 00:25:13,979 --> 00:25:17,716 See, no electric generator is 100% efficient. 377 00:25:17,716 --> 00:25:21,953 And likewise, no electric motor is 100% efficient. 378 00:25:22,187 --> 00:25:28,927 By converting the mechanical energy from the diesel engine to electricity and then back to mechanical energy, 379 00:25:28,960 --> 00:25:32,063 a two-step conversion process is happening 380 00:25:32,063 --> 00:25:39,070 in which a significant percentage of the power output from the engine gets wasted in conversion losses. 381 00:25:39,437 --> 00:25:46,511 Those losses mean that more diesel fuel gets burned than if that two-step conversion process wasn't happening. 382 00:25:46,945 --> 00:25:48,513 But that's the thing. 383 00:25:48,780 --> 00:25:55,387 Locomotives need to get tons of material moving from a dead stop by themselves. 384 00:25:55,554 --> 00:25:58,957 That requires a gargantuan amount of torque, 385 00:25:59,057 --> 00:26:03,795 an amount which a piston engine is not capable of producing on its own. 386 00:26:03,862 --> 00:26:10,669 But it can do it in a roundabout way if you... do precisely what a diesel electric locomotive does. 387 00:26:10,802 --> 00:26:17,042 Locomotives actually need to do that two-step conversion in order to perform their function. 388 00:26:17,075 --> 00:26:23,381 But it is not the most fuel efficient way to move a vehicle using an engine. 389 00:26:23,815 --> 00:26:27,118 Now, what I think is a pretty major source of confusion here 390 00:26:27,118 --> 00:26:31,122 is that many people know trains are very fuel efficient, 391 00:26:31,489 --> 00:26:34,893 but that's nothing to do with the drivetrain. 392 00:26:34,993 --> 00:26:37,562 Trains are inherently fuel efficient 393 00:26:37,562 --> 00:26:40,432 because they have steel wheels running on steel rails 394 00:26:40,432 --> 00:26:43,735 and a middle finger to the concept of aerodynamics. 395 00:26:44,336 --> 00:26:48,206 They're so energy efficient, by virtue of being trains, 396 00:26:48,206 --> 00:26:51,443 that the conversion losses of the diesel-electric drivetrain 397 00:26:51,443 --> 00:26:54,212 essentially don't matter to that use case. 398 00:26:54,346 --> 00:26:56,247 In short, what I want to stress 399 00:26:56,281 --> 00:26:59,284 is just because it's a good idea for a train 400 00:26:59,317 --> 00:27:02,287 does not mean it's a good idea for a car 401 00:27:02,287 --> 00:27:04,589 where aerodynamics do matter a lot, 402 00:27:04,589 --> 00:27:08,159 and it has rubber tires running on a road surface. 403 00:27:08,159 --> 00:27:10,562 And if you're thinking, “Well, fine, 404 00:27:10,562 --> 00:27:13,832 but trains don't have that battery pack to store energy. 405 00:27:13,832 --> 00:27:17,268 So what if the engine could stay in its most efficient 406 00:27:17,335 --> 00:27:18,870 operating profile no matter what, 407 00:27:18,870 --> 00:27:22,307 and whenever it's producing more power than is needed to move the car, 408 00:27:22,474 --> 00:27:25,844 we'll just shuffle that power over to the battery pack to use later?” 409 00:27:26,778 --> 00:27:28,680 Well, that sounds like a good idea, 410 00:27:28,680 --> 00:27:32,283 but charging a battery is another kind of energy conversion, 411 00:27:32,283 --> 00:27:36,755 which is also inherently lossy and thus should also be avoided. 412 00:27:37,155 --> 00:27:41,092 That is why the car doesn't charge the battery with its engine 413 00:27:41,092 --> 00:27:43,395 unless the battery is too low. 414 00:27:43,895 --> 00:27:46,898 When the car is parked as it was in the car wash, 415 00:27:46,898 --> 00:27:50,702 it does use the battery pack like a buffer to power its accessories, 416 00:27:50,702 --> 00:27:53,171 and will run the engine for a few minutes at a time 417 00:27:53,171 --> 00:27:55,106 to charge it back up when it gets low. 418 00:27:55,106 --> 00:27:57,709 In fact, here's exactly what that looks like: 419 00:27:57,709 --> 00:28:01,613 with the vehicle stationary, once the battery pack dips below 40%, 420 00:28:01,746 --> 00:28:05,583 the engine switches on and charges the battery up to about 48%, 421 00:28:05,650 --> 00:28:07,218 a process which takes three minutes. 422 00:28:07,218 --> 00:28:13,491 And then it will shut the engine back off and use the energy it just stored until it's too low again. 423 00:28:13,892 --> 00:28:18,496 But that's just a fancy kind of idling this drivetrain can do 424 00:28:18,530 --> 00:28:21,332 thanks to its fully electric suite of accessories. 425 00:28:21,566 --> 00:28:24,569 Otherwise, when the vehicle is being driven, 426 00:28:24,669 --> 00:28:29,407 the battery pack is charged almost exclusively with regenerative braking. 427 00:28:30,041 --> 00:28:33,278 For those who may not know what regenerative braking is, 428 00:28:33,278 --> 00:28:38,083 well, the electric motor which can propel the car forward via the front wheels does that 429 00:28:38,083 --> 00:28:40,985 when we put electric current through its stator windings, 430 00:28:40,985 --> 00:28:45,757 which in turn generate a rotating magnetic field which spins the motor. 431 00:28:46,024 --> 00:28:51,029 But if the motor is spinning because of something else, it creates 432 00:28:51,062 --> 00:28:56,167 a rotating magnetic field, which we can draw power from using those same stator windings. 433 00:28:56,634 --> 00:29:01,406 That was a long winded way to say “electric motors are also electric generators,” 434 00:29:01,406 --> 00:29:04,075 and when using the motor as a generator, 435 00:29:04,075 --> 00:29:08,980 it will actually slow down the rotational speed of whatever it's attached to. 436 00:29:09,114 --> 00:29:11,349 In this case, the wheels of the car. 437 00:29:11,816 --> 00:29:16,488 In other words, it functions like a brake when generating electricity. 438 00:29:16,488 --> 00:29:18,923 And that's what regenerative braking is. 439 00:29:19,023 --> 00:29:23,995 It's a way to capture energy from the vehicle slowing down and charge the battery pack. 440 00:29:23,995 --> 00:29:29,467 And since you need brakes anyway, this is a free source of energy. 441 00:29:29,467 --> 00:29:33,404 And when the energy is free, conversion losses don't matter. 442 00:29:33,938 --> 00:29:38,409 And so as I drive on the open road where I'm not using the brakes much at all, 443 00:29:38,710 --> 00:29:42,881 the battery pack is just sitting there at about 45% state of charge. 444 00:29:43,281 --> 00:29:47,786 The car doesn't want to dip into that energy because there's no point! 445 00:29:47,786 --> 00:29:50,421 It all came from the engine anyway. 446 00:29:50,989 --> 00:29:56,060 There are only two reasons for this car to use that stored energy: 447 00:29:56,060 --> 00:30:01,699 One, the driver has floored it and wants all 245 horsepower this system can offer. 448 00:30:01,699 --> 00:30:09,107 Or two, the current load on the system causes the engine to go so far outside of its efficiency band 449 00:30:09,107 --> 00:30:16,881 that it would save fuel to borrow from the battery pack and replenish what was borrowed when the engine is no longer under such a heavy load. 450 00:30:17,448 --> 00:30:20,351 But, because of conversion losses, 451 00:30:20,385 --> 00:30:24,422 that second scenario is much rarer than people think it is. 452 00:30:24,689 --> 00:30:28,059 The engine has to get way outside of its efficiency band 453 00:30:28,059 --> 00:30:31,496 for borrowing energy from the battery pack to make any sense, 454 00:30:31,496 --> 00:30:35,366 and that's why the car is not really using the energy in there at all 455 00:30:35,366 --> 00:30:39,204 when it's cruising on the highway, or even during mild acceleration. 456 00:30:39,337 --> 00:30:43,041 If the engine is able to do it by itself efficiently, 457 00:30:43,041 --> 00:30:46,044 that is always the best course of action. 458 00:30:46,511 --> 00:30:49,848 Around town is a completely different story though. 459 00:30:50,148 --> 00:30:53,284 When you're on the highway, a car is constantly working 460 00:30:53,318 --> 00:30:56,154 to push itself forward, but off the highway, 461 00:30:56,187 --> 00:30:59,691 you're going to keep switching back and forth between accelerating and braking. 462 00:31:00,124 --> 00:31:06,564 In a traditional car, friction brakes reduce vehicle speed simply by converting energy into heat. 463 00:31:06,764 --> 00:31:11,002 That works great for stopping the car, but that's all it does. 464 00:31:11,569 --> 00:31:14,906 The battery pack in this car is able to absorb 465 00:31:14,906 --> 00:31:18,309 what would be wasted as heat through regenerative braking, 466 00:31:18,309 --> 00:31:22,146 and since that process doesn't use the engine at all, 467 00:31:22,447 --> 00:31:26,851 whatever energy it can absorb from the vehicle slowing down is free. 468 00:31:27,185 --> 00:31:34,192 So when regen breaking gets the battery pack above 45%, then the car will use that energy to... 469 00:31:35,159 --> 00:31:36,828 help the engine. 470 00:31:37,428 --> 00:31:39,163 This is what I keep getting back to, 471 00:31:39,197 --> 00:31:41,666 and what I'd really like to hammer home today. 472 00:31:41,733 --> 00:31:44,435 If you've been imagining hybrid cars 473 00:31:44,435 --> 00:31:47,372 to use their battery packs something like a bank account 474 00:31:47,372 --> 00:31:52,710 which gets paid into when there's excess energy and borrowed from when there's excess power demand, 475 00:31:53,645 --> 00:31:56,281 this is only kinda sorta of true. 476 00:31:56,648 --> 00:32:04,756 The gasoline in this thing's fuel tank and that engine remain the only source of input power this system has. 477 00:32:04,756 --> 00:32:08,927 So the engine is always going to be the primary propulsion device. 478 00:32:09,093 --> 00:32:15,400 And that's why this minivan almost always starts the engine just after you begin moving. 479 00:32:15,733 --> 00:32:19,704 You have to treat it very gently if you don't want the engine to start 480 00:32:19,704 --> 00:32:26,844 because there just isn't that much energy or power to be had from its small battery pack sitting underneath the front seats. 481 00:32:27,211 --> 00:32:32,150 That battery is not really there to push the car forward when it's got a full charge. 482 00:32:32,150 --> 00:32:38,089 It's just there to augment this engine’s output so the engine itself can stay entirely 483 00:32:38,089 --> 00:32:42,627 within its most efficient operating range in as many circumstances as possible. 484 00:32:42,760 --> 00:32:46,798 In that way, this thing is like the diesel-electric drivetrain 485 00:32:46,798 --> 00:32:49,434 many people imagine hybrid cars should emulate. 486 00:32:49,434 --> 00:32:53,504 And that's why I said “Toyota's already done that.” 487 00:32:53,805 --> 00:32:57,308 But the most efficient way for an engine to run is for it to not. 488 00:32:57,308 --> 00:33:00,945 So when the car has an opportunity to shut the engine off, 489 00:33:00,945 --> 00:33:03,448 it almost always takes it. 490 00:33:03,481 --> 00:33:08,486 For example, pretty much whenever you let off the accelerator, the engine shuts off. 491 00:33:08,586 --> 00:33:11,155 You're no longer commanding forward power, 492 00:33:11,322 --> 00:33:13,758 so there's no point burning any gasoline. 493 00:33:14,158 --> 00:33:19,030 If the car has enough free energy stored in its battery pack from regen braking 494 00:33:19,030 --> 00:33:21,766 and you're commanding only light throttle, 495 00:33:21,766 --> 00:33:26,004 then it might decide to keep the engine off for a good while. 496 00:33:26,237 --> 00:33:30,875 But once your accelerator request exceeds the power output of the battery pack, 497 00:33:31,042 --> 00:33:33,811 the car has to start the engine to keep up. 498 00:33:33,945 --> 00:33:35,246 So it does. 499 00:33:35,747 --> 00:33:39,350 Still, if there's free energy left in the battery pack, 500 00:33:39,384 --> 00:33:43,287 the car will sometimes kind of flip the script and use the engine 501 00:33:43,287 --> 00:33:47,892 to augment the limited power from the electric side of its drivetrain. 502 00:33:48,192 --> 00:33:51,062 Here you can see the battery state of charge dropping 503 00:33:51,062 --> 00:33:53,297 even though the engine is running. 504 00:33:53,464 --> 00:33:56,734 It's doing that because it's got some free energy to use up, 505 00:33:56,734 --> 00:34:00,304 so it might as well do that and take some load off the engine, 506 00:34:00,304 --> 00:34:05,309 which has the side bonus of keeping the engine in a really energy efficient operating condition 507 00:34:05,343 --> 00:34:08,913 even though the vehicle is accelerating and climbing a hill. 508 00:34:09,614 --> 00:34:14,685 If you'd like to see in data and hear from a microphone what the powertrain of this vehicle 509 00:34:14,685 --> 00:34:17,488 does under a wide variety of circumstances, 510 00:34:17,555 --> 00:34:21,526 you can check out this Sights and Sounds video I've released on my second channel. 511 00:34:21,659 --> 00:34:26,197 I put an audio recorder in the engine compartment of this thing on my way to Hammond, 512 00:34:26,197 --> 00:34:31,502 and being able to hear the engine and motors so clearly revealed some interesting things 513 00:34:31,502 --> 00:34:35,039 about how the system makes decisions and how it works in general. 514 00:34:35,640 --> 00:34:37,408 But to wrap this video up, 515 00:34:37,442 --> 00:34:41,846 now it's time to talk about the mechanical details of Toyota's hybrid system, 516 00:34:41,846 --> 00:34:48,019 because what I've talked about so far might very well make it sound fragile and dauntingly complex, 517 00:34:48,119 --> 00:34:51,923 when in fact the system is so mechanically simple 518 00:34:52,256 --> 00:34:54,392 it almost hurts to think about. 519 00:34:54,826 --> 00:34:59,797 So, here's the wildest thing about how Toyota designed their hybrid system: 520 00:35:00,098 --> 00:35:05,436 The engine in this vehicle is not actually connected to the front wheels. 521 00:35:05,436 --> 00:35:08,639 And yet, the engine in this vehicle 522 00:35:08,639 --> 00:35:12,009 is permanently coupled to the front wheels. 523 00:35:13,211 --> 00:35:17,081 To explain that apparent contradiction, let's put the Cube up on the lift 524 00:35:17,081 --> 00:35:20,685 and let its engine spin the front wheels while it's off the ground. 525 00:35:21,185 --> 00:35:23,588 With the engine running and the car in gear, 526 00:35:23,588 --> 00:35:26,691 both front tires are turning at equal speed. 527 00:35:26,824 --> 00:35:32,263 But because the car has to navigate turns where one wheel will be rotating faster than the other, 528 00:35:32,563 --> 00:35:38,069 the power coming from the engine and transmission is delivered through what's called a differential. 529 00:35:38,469 --> 00:35:41,239 It's not important to know the mechanical details of that, 530 00:35:41,239 --> 00:35:47,078 but the differential is designed to split the power output of the engine between the two wheels, 531 00:35:47,111 --> 00:35:50,148 while also allowing them to spin independently. 532 00:35:50,348 --> 00:35:54,185 And the ordinary differential has a bit of a quirk: 533 00:35:54,318 --> 00:35:58,589 I can easily stop one of the two wheels with my hands, 534 00:35:58,589 --> 00:36:03,394 and now that I've done that, the other wheel has sped up. 535 00:36:03,861 --> 00:36:06,631 Note that the engine didn't get any faster, 536 00:36:06,631 --> 00:36:10,568 it's still just idling. But by preventing one wheel from moving, 537 00:36:10,568 --> 00:36:13,704 the other wheel is now spinning twice as fast. 538 00:36:14,005 --> 00:36:15,873 But it gets even weirder. 539 00:36:16,107 --> 00:36:19,510 If I start to rotate the wheel I'm holding backwards, 540 00:36:19,510 --> 00:36:22,980 the free spinning wheel on the other side spins even faster! 541 00:36:22,980 --> 00:36:28,753 And if I then start pushing the wheel forward again but faster than the engine wants to spin it, 542 00:36:28,786 --> 00:36:31,622 the wheel on the other side starts to slow down. 543 00:36:31,622 --> 00:36:34,525 In fact, if I can spin the tire fast enough, 544 00:36:34,525 --> 00:36:37,995 I can get the other tire to come to a complete stop. 545 00:36:38,729 --> 00:36:40,831 What's this got to do with the Sienna? 546 00:36:41,299 --> 00:36:43,000 Well, believe it or not, 547 00:36:43,034 --> 00:36:46,871 this phenomenon is at the heart of Toyota's hybrid system. 548 00:36:46,871 --> 00:36:51,409 But rather than use the engine to spin a pair of wheels through a differential, 549 00:36:51,742 --> 00:36:55,846 the engine spins the rotors of two electric motors. 550 00:36:56,314 --> 00:37:00,451 I'm only going to give you a very surface-level explanation of this, but look. 551 00:37:00,484 --> 00:37:01,986 That's it. 552 00:37:02,320 --> 00:37:06,224 Watch this video from the Weber Auto YouTube channel if you want the full explanation. 553 00:37:06,224 --> 00:37:09,794 But those parts on the table are the whole thing. 554 00:37:09,994 --> 00:37:13,064 That is Toyota's Hybrid Synergy Drive. 555 00:37:13,064 --> 00:37:17,201 It's just two electric motors and a planetary gearset. 556 00:37:17,268 --> 00:37:18,469 That's it. 557 00:37:18,636 --> 00:37:24,075 The only parts not shown are the stators and wiring which actually drive the electric motors 558 00:37:24,075 --> 00:37:26,844 and the case which holds all this stuff together. 559 00:37:27,545 --> 00:37:28,946 Oh, and also in reality, 560 00:37:28,946 --> 00:37:32,049 this would all be covered in oil for lubrication and cooling. 561 00:37:32,283 --> 00:37:37,421 But when it comes to the spinny bits which connect the engine and motors to the wheels of the car, 562 00:37:37,555 --> 00:37:40,324 there are literally just three: 563 00:37:40,758 --> 00:37:43,160 the parts of a planetary gearset. 564 00:37:43,628 --> 00:37:48,766 The crankshaft of the engine spends the planet carrier of the planetary gear set, 565 00:37:48,966 --> 00:37:55,773 a small electric motor generator unit known as MG1 spins the sun gear of that gearset, 566 00:37:55,773 --> 00:38:01,212 and a larger electric motor, MG2, spins the ring gear of that gearset, 567 00:38:01,212 --> 00:38:05,583 which is itself coupled to the wheels of the car through a conventional differential. 568 00:38:06,317 --> 00:38:06,784 Okay, 569 00:38:06,784 --> 00:38:10,554 it's time to get out the whiteboard because I need something to point at 570 00:38:10,554 --> 00:38:12,990 as I explain the details of how this works. 571 00:38:12,990 --> 00:38:15,226 This drawing is not at all accurate 572 00:38:15,226 --> 00:38:18,696 when it comes to how these three parts are arranged and fit together, 573 00:38:18,696 --> 00:38:23,000 but that's kind of the whole problem with describing Toyota's system. 574 00:38:23,034 --> 00:38:26,337 What each part by itself does is very simple, 575 00:38:26,337 --> 00:38:29,540 and how they're coupled together is also very simple. 576 00:38:29,540 --> 00:38:33,978 But the choreography of the dance they're performing to make the car go 577 00:38:34,078 --> 00:38:35,179 is not. 578 00:38:35,179 --> 00:38:37,882 Here is my best (and revised) attempt 579 00:38:37,882 --> 00:38:39,984 at painting the complete picture for you. 580 00:38:40,484 --> 00:38:42,053 So here's the engine. 581 00:38:42,053 --> 00:38:44,855 Here's MG1 and here's MG2. 582 00:38:45,156 --> 00:38:51,329 What connects this all together is that planetary gearset which acts to split the output power 583 00:38:51,329 --> 00:38:55,366 from the engine between the rotors of MG1 and MG2. 584 00:38:55,966 --> 00:38:58,602 What I think is the most confusing thing 585 00:38:58,636 --> 00:39:02,640 to wrap your head around here is that all three of these devices 586 00:39:02,640 --> 00:39:04,809 can move under their own power. 587 00:39:05,676 --> 00:39:08,479 MG1 and MG2 are both electrical generators, 588 00:39:08,479 --> 00:39:11,449 but they are also both electric motors. 589 00:39:11,649 --> 00:39:15,886 The engine burns fuel to spin and the motors use electricity to spin, 590 00:39:15,886 --> 00:39:20,291 but the car is in direct control of all three of these things 591 00:39:20,291 --> 00:39:23,427 and can spin them at whatever speed it desires. 592 00:39:23,961 --> 00:39:28,165 Now for a moment, I want you to forget that these are motors, 593 00:39:28,165 --> 00:39:30,401 because you can think of this arrangement 594 00:39:30,401 --> 00:39:33,070 as equivalent to a diesel electric drivetrain. 595 00:39:33,070 --> 00:39:36,907 But rather than connect an engine to a single electrical generator, 596 00:39:36,907 --> 00:39:40,177 it's been connected to two of them at the same time 597 00:39:40,211 --> 00:39:42,313 through that planetary gearset. 598 00:39:42,546 --> 00:39:44,949 We refer to that gearset generically 599 00:39:44,949 --> 00:39:48,119 as a power splitdevice, because that's what it does. 600 00:39:48,152 --> 00:39:52,256 And it operates exactly like the differential in a typical car. 601 00:39:52,590 --> 00:39:55,159 That is why I used the Cube as a demo. 602 00:39:55,159 --> 00:39:57,495 And just as I can make one of the Cube’s 603 00:39:57,495 --> 00:40:00,531 tires speed up just by stopping the other one, 604 00:40:00,598 --> 00:40:04,402 a Toyota Hybrid can make one of its two generators speed up 605 00:40:04,402 --> 00:40:06,904 just by slowing the other one down. 606 00:40:07,438 --> 00:40:09,140 Now, that might seem trivial, 607 00:40:09,140 --> 00:40:11,709 but what I haven't drawn into this diagram yet 608 00:40:11,709 --> 00:40:14,445 is that one of those generators, MG2, 609 00:40:14,445 --> 00:40:17,481 is also coupled to the wheels of the car. 610 00:40:18,015 --> 00:40:23,921 So this one is not actually free to spin at whatever speed it wants to. 611 00:40:23,988 --> 00:40:27,091 Its rotational speed depends on how fast 612 00:40:27,091 --> 00:40:29,760 the wheels and thus the car are going. 613 00:40:29,827 --> 00:40:34,064 And in fact when the car is stopped, this can't spin at all. 614 00:40:34,465 --> 00:40:37,468 But that doesn't mean the engine can't spin. 615 00:40:38,202 --> 00:40:40,137 MG1 is always free to rotate. 616 00:40:40,137 --> 00:40:43,140 So if MG2 cannot, what will happen 617 00:40:43,140 --> 00:40:46,010 is that all of the engine's rotational output 618 00:40:46,043 --> 00:40:50,381 gets sent to MG1 and this will spin really fast. 619 00:40:50,414 --> 00:40:53,784 It's just like me holding this tire stationary. 620 00:40:53,818 --> 00:40:59,089 The engine output is all going to the other tire or in a Toyota hybrid, 621 00:40:59,089 --> 00:41:03,060 if the wheels are stopped and MG2 cannot spin, 622 00:41:03,060 --> 00:41:06,630 then all of the engine output will go to MG1. 623 00:41:06,997 --> 00:41:11,535 But of course, MG1 isn't a tire, it's an electrical generator. 624 00:41:11,535 --> 00:41:15,639 And MG2 isn't just an electrical generator, 625 00:41:15,639 --> 00:41:17,875 it is also a motor. 626 00:41:18,175 --> 00:41:22,213 So whenever a Toyota hybrid wants to move forward, 627 00:41:22,213 --> 00:41:27,418 it will simply use the engine to spin the rotor of MG1 really fast, 628 00:41:27,418 --> 00:41:31,322 which will generate electricity. And then it will shuttle that electricity 629 00:41:31,322 --> 00:41:35,159 over to MG2 in order to make it spin. 630 00:41:35,392 --> 00:41:38,128 Since MG2 is connected to the front 631 00:41:38,162 --> 00:41:40,664 wheels, that's going to push the car forward 632 00:41:40,664 --> 00:41:43,400 or indeed backwards. 633 00:41:43,400 --> 00:41:45,936 Reverse gear is accomplished simply 634 00:41:45,936 --> 00:41:49,673 by spinning the rotor of MG2 backwards. 635 00:41:49,807 --> 00:41:52,443 But, when the car is moving forward... 636 00:41:52,743 --> 00:41:55,379 well, you may notice that what I've just described 637 00:41:55,379 --> 00:41:58,082 here is a diesel electric locomotive. 638 00:41:58,082 --> 00:42:01,685 And earlier I went on a tirade about why that is a silly way 639 00:42:01,685 --> 00:42:04,455 to move a car because of conversion losses. 640 00:42:04,688 --> 00:42:09,360 Well, that is the brilliant thing about the powersplit device. 641 00:42:09,593 --> 00:42:12,897 If the engine is running at a fixed speed 642 00:42:12,897 --> 00:42:18,502 and one of these two motors slows down, then the powersplit device 643 00:42:18,502 --> 00:42:22,540 will mechanically force the other one to speed up. 644 00:42:23,173 --> 00:42:25,676 Now, to explain why this is important, well, 645 00:42:25,709 --> 00:42:28,312 remember how regenerative braking works? 646 00:42:28,479 --> 00:42:30,548 When we use a motor as a generator, 647 00:42:30,548 --> 00:42:34,752 It creates an opposing mechanical force on the thing which is spinning it. 648 00:42:34,752 --> 00:42:38,489 And that force acts to slow the spinning thing down. 649 00:42:38,756 --> 00:42:43,060 During regenerative braking, the slowing rotor of MG2 650 00:42:43,160 --> 00:42:46,597 slows down the wheels of the car, acting like a brake. 651 00:42:46,697 --> 00:42:52,736 But the same thing happens as MG1 generates electricity using the engine. 652 00:42:52,937 --> 00:42:57,875 As the stator windings surrounding MG1's rotor harness power 653 00:42:57,875 --> 00:43:03,013 from the rotating magnetic field the engine is producing by spinning this rotor, 654 00:43:03,013 --> 00:43:08,519 an opposing torque is generated which will try to slow the rotor down. 655 00:43:08,519 --> 00:43:13,691 But because of the powersplit device coupling all of this together, 656 00:43:13,757 --> 00:43:21,365 even if the engine is running at a constant speed, MG1 slowing down causes MG2, 657 00:43:21,365 --> 00:43:25,436 and thus the wheels of the car to speed up. 658 00:43:26,003 --> 00:43:31,775 The fact that the relative rotational speed of the engine and wheels can be altered on the fly 659 00:43:31,809 --> 00:43:38,215 simply by speeding up or slowing down the speed of MG1 is what makes this system functionally equivalent 660 00:43:38,215 --> 00:43:40,551 to a continuously variable transmission. 661 00:43:40,884 --> 00:43:44,421 And that's why Toyota calls it an eCVT. 662 00:43:45,189 --> 00:43:49,360 Personally, I don't think they're doing themselves any favors using that term, 663 00:43:49,360 --> 00:43:56,166 since most people who know the term CVT associate it with horrible things which are mechanically fragile 664 00:43:56,166 --> 00:43:58,769 when this is anything but. 665 00:43:58,769 --> 00:44:04,341 The powersplit device has no gears to change, or clutch packs to wear out, or weird 666 00:44:04,375 --> 00:44:07,811 belt chain things to move between two cones. 667 00:44:08,078 --> 00:44:11,148 It's as mechanically simple as you could possibly imagine, 668 00:44:11,148 --> 00:44:14,084 and all of its parts are permanently coupled together. 669 00:44:14,151 --> 00:44:17,087 Yet it does all the stuff we've been talking about. 670 00:44:17,321 --> 00:44:20,124 And what's really remarkable to me about this system 671 00:44:20,124 --> 00:44:23,727 is that it all fits into a package which doesn't even look 672 00:44:23,727 --> 00:44:26,263 that different from a traditional transmission. 673 00:44:26,263 --> 00:44:28,132 That's why nothing under the hood of this car 674 00:44:28,165 --> 00:44:31,301 looks all that out of the ordinary, except for the fact that the gearbox 675 00:44:31,301 --> 00:44:34,204 has some beefy wires coming out of it. 676 00:44:34,638 --> 00:44:35,773 Now, in reality, 677 00:44:35,773 --> 00:44:39,810 and this is another thing which makes holding all this together in your head pretty difficult, 678 00:44:39,910 --> 00:44:43,580 We don't actually need the rotational speeds to change 679 00:44:43,580 --> 00:44:47,017 in order to transmit power from the engine to the wheels. 680 00:44:47,284 --> 00:44:49,853 What matters is the opposing torque 681 00:44:49,887 --> 00:44:52,790 MG1 is putting on the engine crankshaft, 682 00:44:52,790 --> 00:44:57,594 and that torque can be constant while the speeds are constant, too. 683 00:44:58,295 --> 00:45:01,665 Remember, it's really easy to stop this spinning tire 684 00:45:01,665 --> 00:45:06,170 because an ordinary open differential will send all the engine power 685 00:45:06,203 --> 00:45:09,640 over to whichever tire has the least traction. 686 00:45:09,807 --> 00:45:11,041 It's kind of a bummer, really, 687 00:45:11,041 --> 00:45:13,777 and that's why limited slip differentials are a thing. 688 00:45:13,777 --> 00:45:18,415 But luckily for us, a similar thing happens with the planetary gearset. 689 00:45:18,415 --> 00:45:23,454 So if MG1 is producing an opposing torque on the engine, 690 00:45:23,454 --> 00:45:29,426 rather than actually slow the engine down, that torque just gets shuttled over into MG2. 691 00:45:29,426 --> 00:45:33,864 And thus the act of using MG1 as a generator 692 00:45:33,864 --> 00:45:38,569 actually causes the engine to push directly on the wheels of the car. 693 00:45:38,902 --> 00:45:41,939 This is why the Toyota hybrid system, in my opinion, 694 00:45:42,005 --> 00:45:47,644 can't neatly be classified as either a series hybrid or a parallel hybrid. 695 00:45:47,845 --> 00:45:49,913 It's actually somewhere in the middle. 696 00:45:50,547 --> 00:45:55,419 While there is a mechanical connection between the engine crankshaft and the wheels, 697 00:45:55,586 --> 00:45:58,522 the engine can't actually push the wheels forward 698 00:45:58,522 --> 00:46:03,160 unless the hybrid system is doing something to slow down MG1. 699 00:46:03,527 --> 00:46:07,431 Otherwise, it's equivalent to a car with one tire off the ground. 700 00:46:07,598 --> 00:46:11,602 All the engine will do in that case is spin that tire really fast 701 00:46:11,602 --> 00:46:13,537 and the car won't actually move. 702 00:46:14,304 --> 00:46:20,344 Now, this means there are some conversion losses happening in Toyota's system, but 703 00:46:20,377 --> 00:46:25,582 how much and exactly where they're occurring is way above my pay grade. 704 00:46:26,083 --> 00:46:30,354 My mental model suggests the car doesn't have to do very much work 705 00:46:30,354 --> 00:46:34,158 to cause the engine to mechanically contribute, so the losses are minimal, 706 00:46:34,158 --> 00:46:36,860 but I have no real basis for that 707 00:46:36,860 --> 00:46:42,099 other than the stellar real world fuel economy most Toyota hybrids have historically attained. 708 00:46:42,599 --> 00:46:45,969 Now, that was the first time I've even mentioned the terms 709 00:46:45,969 --> 00:46:49,173 series hybrid and parallel hybrid in this video. 710 00:46:49,173 --> 00:46:53,277 And that's because to the end user, the difference doesn't really matter. 711 00:46:53,977 --> 00:46:58,582 But at the same time, the difference is kind of the heart of the point 712 00:46:58,582 --> 00:47:00,551 I'm trying to make in this video. 713 00:47:01,118 --> 00:47:04,221 Toyota's hybrid system is a parallel hybrid system, 714 00:47:04,221 --> 00:47:08,091 because the engine can mechanically contribute to the movement of the car, 715 00:47:08,091 --> 00:47:12,062 and I hope by now you understand why this is a good thing. 716 00:47:12,896 --> 00:47:14,998 Series hybrids are different. 717 00:47:15,065 --> 00:47:18,268 Series hybrids have an engine which can only power 718 00:47:18,268 --> 00:47:21,638 an electrical generator, and the electricity which is generated 719 00:47:21,638 --> 00:47:23,574 that way will be used to charge a battery 720 00:47:23,574 --> 00:47:26,176 or power electric motors to move the car. 721 00:47:27,311 --> 00:47:32,549 But unless you have a very good reason to design a system that way, 722 00:47:32,783 --> 00:47:35,319 this is not a good idea. 723 00:47:35,652 --> 00:47:38,455 Diesel electric locomotives have a very good reason 724 00:47:38,455 --> 00:47:41,758 to decouple the engine from the motors: for torque. 725 00:47:41,859 --> 00:47:45,295 And in theory, a future extended-range electric vehicle 726 00:47:45,329 --> 00:47:48,198 might benefit from separating the engine and generator 727 00:47:48,198 --> 00:47:49,466 from the rest of the car. 728 00:47:50,434 --> 00:47:51,869 But I promise, 729 00:47:51,869 --> 00:47:57,474 such a future vehicle is not going to benefit from that from a fuel efficiency standpoint. 730 00:47:57,674 --> 00:48:01,879 There could very well be a good packaging reason to design the vehicle that way. 731 00:48:01,912 --> 00:48:05,816 But if you're insisting on using the engine primarily as a generator 732 00:48:05,816 --> 00:48:10,420 for any other reason, I would argue you're making a mistake. 733 00:48:11,021 --> 00:48:15,659 And we have a perfect example of such a mistake with my previous car, 734 00:48:15,859 --> 00:48:17,861 a Gen1 Chevy Volt. 735 00:48:18,262 --> 00:48:22,366 For reasons which are unclear but probably rhyme with General Motors, 736 00:48:22,366 --> 00:48:28,505 that car was designed explicitly to operate as a series hybrid in most driving conditions. 737 00:48:29,006 --> 00:48:31,708 Well, after its battery charge had been depleted. 738 00:48:31,708 --> 00:48:33,844 The whole point of the Chevy Volt was to be 739 00:48:33,844 --> 00:48:37,214 an electric car first with a small electric range, 740 00:48:37,214 --> 00:48:40,517 but which also had a gas powered range extender 741 00:48:40,517 --> 00:48:43,053 to give it unlimited range for road trips. 742 00:48:43,220 --> 00:48:46,990 But once you had run out of charge and it started up its engine, 743 00:48:47,591 --> 00:48:49,593 you discovered that the car wouldn't 744 00:48:49,593 --> 00:48:53,063 keep the engine running when you were cruising at moderate speeds. 745 00:48:53,063 --> 00:48:56,099 Instead, it would run the engine in spurts 746 00:48:56,099 --> 00:48:59,002 where it was producing way more power than the car 747 00:48:59,036 --> 00:49:02,539 actually needed to drive, say, 40 miles an hour, 748 00:49:02,639 --> 00:49:05,309 and then it would send the excess power 749 00:49:05,309 --> 00:49:07,544 into the battery pack to use later. 750 00:49:07,544 --> 00:49:11,615 So after a while it would shut off the engine and use up that energy. 751 00:49:11,882 --> 00:49:16,253 But because there were four steps of energy conversion going on there: 752 00:49:16,253 --> 00:49:19,790 engine to electricity, excess electricity to charge the battery, 753 00:49:19,823 --> 00:49:22,159 discharging the battery to get electricity out of it, 754 00:49:22,159 --> 00:49:25,162 and then using that electricity to spin an electric motor, 755 00:49:25,462 --> 00:49:28,966 It got surprisingly mediocre fuel economy. 756 00:49:29,333 --> 00:49:32,469 The Gen 1 Volt, on premium gas to boot, 757 00:49:32,469 --> 00:49:37,574 could only manage 35 miles per gallon city 40 highway. 758 00:49:37,874 --> 00:49:42,112 So that car, which was a lot smaller than a minivan, 759 00:49:42,412 --> 00:49:45,882 got basically the same fuel economy as this minivan. 760 00:49:45,949 --> 00:49:49,987 Worse, from a dollars perspective, if you actually used premium fuel. 761 00:49:51,088 --> 00:49:52,589 That's pretty terrible! 762 00:49:52,589 --> 00:49:57,594 But given how that car was designed to operate, that's to be expected. 763 00:49:57,861 --> 00:50:06,103 Even with the flexibility of electric motors and fancy electronics, series hybrids are just less efficient than parallel hybrids. 764 00:50:06,136 --> 00:50:09,740 If you can use the engine to push the wheels of the car, 765 00:50:09,873 --> 00:50:13,343 you should be doing that to avoid conversion losses. 766 00:50:13,810 --> 00:50:20,384 Nissan, for some reason, is supposedly about to release a new series hybrid drivetrain with the Nissan Rogue, 767 00:50:20,384 --> 00:50:22,819 and I don't really understand why they're doing that, but 768 00:50:22,886 --> 00:50:26,023 we'll see what kind of fuel economy they can get out of it. 769 00:50:26,089 --> 00:50:29,726 My guess is, like the Volt, it's going to be decent, 770 00:50:29,726 --> 00:50:31,862 but far from exceptional. 771 00:50:32,462 --> 00:50:38,568 By the way, it's very possible there's a patent reason that GM chose to build the Volt the way they did. 772 00:50:38,635 --> 00:50:42,439 Their Voltec drive system was actually remarkably similar 773 00:50:42,439 --> 00:50:45,008 in many ways to Toyota's hybrid system. 774 00:50:45,008 --> 00:50:48,979 It, too, fit two electric motor generator units into a package 775 00:50:48,979 --> 00:50:52,249 which replaced the conventional transmission, and in a layout 776 00:50:52,249 --> 00:50:55,752 which was really similar to what's in this minivan. 777 00:50:56,186 --> 00:51:00,791 They could very well have gotten into legal trouble had they made the design any more similar. 778 00:51:00,791 --> 00:51:04,628 And Ford ended up licensing Toyota's hybrid technology 779 00:51:04,628 --> 00:51:08,398 because Ford also ended up making a very similar design. 780 00:51:08,398 --> 00:51:13,370 In fact, the hybrid Ford Maverick is basically a Prius, but truck shaped. 781 00:51:13,837 --> 00:51:17,507 By now, most of the original Toyota patents will have expired, so 782 00:51:17,541 --> 00:51:21,945 I don't know how much this matters in 2026, but I wanted to mention it. 783 00:51:22,312 --> 00:51:23,447 I'm about to wrap up, 784 00:51:23,447 --> 00:51:29,019 but in case any of you out there need another reason to see this as a really cool way to do things 785 00:51:29,052 --> 00:51:32,055 well, remember how this van is all wheel drive? 786 00:51:32,355 --> 00:51:35,392 Toyota made that happen in a really fascinating way, 787 00:51:35,392 --> 00:51:39,129 which is only possible because this is a hybrid electric vehicle. 788 00:51:39,296 --> 00:51:42,732 They just slapped a third electric motor on the rear axle. 789 00:51:43,133 --> 00:51:44,468 This thing's not very powerful. 790 00:51:44,468 --> 00:51:46,203 It's only about 40 horsepower. 791 00:51:46,203 --> 00:51:48,772 But that's plenty to get the car unstuck 792 00:51:48,772 --> 00:51:52,609 or to give it some extra traction in wet, slippery conditions. 793 00:51:52,676 --> 00:51:56,513 And because this thing normally just tootles along without doing anything, 794 00:51:56,546 --> 00:52:00,117 there's virtually no efficiency penalty to having it. 795 00:52:00,183 --> 00:52:02,652 The EPA rating between the front wheel drive 796 00:52:02,652 --> 00:52:06,156 and all wheel drive versions of this car varies by exactly 797 00:52:06,289 --> 00:52:10,961 one mile per gallon, so doing it this way is pretty clever. 798 00:52:11,261 --> 00:52:16,633 And Toyota’s hybrid drivetrain design has another pretty huge trick up its sleeve: 799 00:52:16,633 --> 00:52:22,139 It can be tweaked to make a car a plug-in hybrid trivially. 800 00:52:22,139 --> 00:52:28,411 This van's main electric motor, MG2, can actually produce 180 horsepower. 801 00:52:28,678 --> 00:52:31,047 The reason the hybrid system can only provide 802 00:52:31,047 --> 00:52:34,518 about 60 horsepower of boost power to the engine 803 00:52:34,551 --> 00:52:37,754 is a limitation of the battery pack it's been equipped with. 804 00:52:37,821 --> 00:52:41,892 If it had a larger battery pack capable of delivering more power, 805 00:52:41,925 --> 00:52:46,696 this thing could operate in all-electric mode with pretty decent power on tap. 806 00:52:46,696 --> 00:52:52,936 And that's why many of Toyota's plug-in hybrids really are just their standard hybrids. 807 00:52:52,936 --> 00:52:54,671 But with a larger battery pack 808 00:52:54,671 --> 00:52:57,741 which can be recharged using off board power. 809 00:52:58,375 --> 00:53:01,811 However, something I want you to know is that plug in hybrids 810 00:53:01,811 --> 00:53:05,749 only make sense for those that can reliably charge them at home 811 00:53:05,749 --> 00:53:08,518 or at work with cheap electricity, 812 00:53:08,885 --> 00:53:12,322 because when plug in hybrids switch to gasoline power, 813 00:53:12,355 --> 00:53:15,225 they have a pretty significant fuel economy penalty 814 00:53:15,225 --> 00:53:17,861 compared to their non plug in counterparts. 815 00:53:18,228 --> 00:53:21,998 This is mostly due to the fact that they're carrying more weight around with them, 816 00:53:21,998 --> 00:53:24,968 since they have a much larger and heavier battery pack, 817 00:53:25,035 --> 00:53:31,274 though changes to the drivetrain design to prioritize engine-less operation can also make fuel economy worse. 818 00:53:31,541 --> 00:53:35,445 So if you're not able to charge your car every day, 819 00:53:35,478 --> 00:53:38,682 either at home or at work with cheap electricity, 820 00:53:39,149 --> 00:53:41,084 don't consider a plug in hybrid. 821 00:53:41,117 --> 00:53:45,689 There's no point having those extra batteries unless you can actually use them. 822 00:53:46,289 --> 00:53:49,025 Personally though, as I'm sure many of you already know, 823 00:53:49,025 --> 00:53:52,062 I'm over the internal combustion engine. 824 00:53:52,162 --> 00:53:54,497 Since I can charge my car at home, 825 00:53:54,497 --> 00:53:58,668 I’d much rather that car just have more batteries 826 00:53:58,668 --> 00:54:01,304 and not have such things as a catalytic converter 827 00:54:01,304 --> 00:54:06,543 or a transmission, or a fuel tank, fuel pump, fuel injectors, or fuel. 828 00:54:06,943 --> 00:54:09,713 But while we are still figuring out how to undertake 829 00:54:09,713 --> 00:54:15,218 the monumental task of getting wires from buildings to parking lots, 830 00:54:15,719 --> 00:54:18,521 well, charging a car will be less convenient 831 00:54:18,521 --> 00:54:20,090 than refueling for many people. 832 00:54:20,090 --> 00:54:22,826 So if you're going to have a car with an engine, 833 00:54:23,093 --> 00:54:25,929 why not make the smarter choice and get one with an engine 834 00:54:25,929 --> 00:54:28,698 designed to burn as little fuel as possible? 835 00:54:29,199 --> 00:54:33,703 Gas costs money, you know, and sometimes it gets very expensive very quickly. 836 00:54:34,638 --> 00:54:40,010 Making choices which lower your ongoing costs, I think, should always be in fashion 837 00:54:40,343 --> 00:54:43,780 because your future self is worth treating, too. 838 00:54:45,415 --> 00:54:47,851 ♫ losslessly smooth jazz ♫ 839 00:54:49,052 --> 00:54:49,853 whoop 840 00:54:50,020 --> 00:54:53,390 And because this thing normally just tootles along without doing anything, 841 00:54:53,423 --> 00:54:57,661 There's virtually no penalty to having it. The miles per gallon - 842 00:54:57,761 --> 00:54:59,129 Oh, I'm looking at my face. 843 00:54:59,162 --> 00:55:00,030 That's silly. 844 00:55:00,030 --> 00:55:03,466 There are still, woo. hoo. hoo! 845 00:55:04,501 --> 00:55:07,037 And I backed the teleprompter up too much. 846 00:55:07,637 --> 00:55:08,838 Farts. 847 00:55:08,872 --> 00:55:10,607 Farts. Farts! 848 00:55:10,607 --> 00:55:14,911 ...replenished whenever it makes sense to do so from an efficiency perspective. 849 00:55:15,445 --> 00:55:16,913 Why did you add that line? 850 00:55:16,913 --> 00:55:20,717 I should have written that differently and I just figured out how. 851 00:55:20,850 --> 00:55:21,718 That. 852 00:55:21,718 --> 00:55:23,086 Why'd you stop? 853 00:55:23,119 --> 00:55:25,021 You weren't supposed to stop, you turd. 854 00:55:25,188 --> 00:55:26,556 this line could use a revision. 855 00:55:26,556 --> 00:55:27,957 I'm doing it on the fly. 856 00:55:27,991 --> 00:55:29,426 This may be a mistake. 857 00:55:29,626 --> 00:55:32,128 with a larger battery pack capable of.