Toyota Claims Bigger Engine are Better for Fuel Economy

by Benjamin Jones on March 6, 2009


I was just looking through some of the official Toyota videos on youtube when I happened to stumble across this explanation of some of the tech in the new Prius. I already knew that Toyota had made some changes to the engine to favor a more powerful, quicker Prius. Despite that, the car received a bump in its EPA ratings.

That’s not too strange, however. It’s common for car makers to split the difference in efficiency gains between power and fuel economy to try to please both of those desires. Usually, however, those same car makers will claim, instead of being honest about splitting the difference, that more power is somehow better for fuel economy.

Toyota is doing the same thing here with the Prius. By claiming that the engine has to work less since it’s bigger, the company is basically lying. If larger engines actually got better fuel economy, you wouldn’t see a sliding scale from small engines with good fuel economy to large engines with poor fuel economy when looking at all cars currently available.

It’s most likely that the improvements in efficiency are due to Toyota’s efforts to reduce aerodynamic and parasitic drag on the engine. So don’t be deceived into thinking that faster and bigger is all of a sudden more fuel efficient.

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1 mike March 8, 2009 at 8:17 am

if your fuel input is limited you can increase power by increasing the efficiency of the engine. some measures used to increase power along these lines also increase efficiency…

2 Benjamin Jones March 8, 2009 at 5:55 pm

Thanks for the comment Mike. I will agree with you on that point, however, I tend to think we’re being greenwashed a little bit by Toyota here, especially in the way is was stated. While I agree that there are many specific applications of this Toyota’s lack of context made it unfortunately ambiguous what they actually meant.

3 shovel March 10, 2009 at 10:02 am

While bigger isn’t automatically more efficient, I do strongly feel that an adequate engine working within its efficient range is going to return better fuel efficiency than an inadequate engine working its tail off.

I, and many others have replaced aging 2.8L engines in Isuzu 4×4’s with 3.4L engines (same block, same manifolds, etc… so the swap is dead easy) and report nearly universal improvements in fuel economy, above the original EPA estimates for the vehicle.

4 Jim Bullis, Miastrada Co. April 19, 2009 at 10:28 am

Toyota seems weak when it comes to ability to explain its own car. I hate to say it but it seems like they are dumbing down for the American market. We are not accustomed to much technical detail from our own companies. After all, about all we have is a fashion industry dressing up the same old car underneath.

One of the biggest advantages of the hybrid can be that it enables the engine to operate over a much narrower range of speeds and power output levels . This enables a tuning process that can be very effective. The larger Toyota engine may be allowing a slightly better tuning to happen. They also may use the battery to even further narrow the range of speeds and power output levels needed. The weight of the engine might or might not go up.

As for regular car engines, putting a bigger engine in a car might not increase fuel usage beyond the weight effect if it is not pressed to a higher level output. Of course, it is very hard to not accelerate faster when it can be easily done. This gets to the question of how much we can depend on human drivers to make objective tests.

5 Terry Bates September 28, 2009 at 7:05 pm

What Toyota says makes sense gang. It’s the same thing G.M. discovered with their 33MPG Cobalt. When they came up with the high MPG Cobalt XFE one of the things they had to do was to bump the engine size to a 2.2 Liter from a 2.0 Liter. Then add a new gear ratio, 5-speed stick shift, and low resistance tires and finally Chevy has built a car that I swear to you is currently getting me 45MPG. (EPA says 37, up to 44 possible). Sometimes too small an engine burns more fuel than one a little bit bigger, depending on the weight of the car.

6 Rich Palais October 10, 2009 at 2:21 am

I have been saying for YEARS, the same exact thing as what others and experts are now also saying. Namely, that too small of an engine in a vehicle will get worse fuel economy than a slightly larger and more powerful motor will allow in the same vehicle. Having a true situation in which the motor has to work less hard to propel the vehicle allows for improved fuel economy, let alone the increased fun factor in driving the same car. This is all a “no-brainer” to me. More power, better fuel economy and lots more fun to drive. Why wouldn’t all car manufacturers do what Toyota and GM are doing in this area? It all makes total sense to me.

7 Cam October 21, 2009 at 6:25 pm

Capacity isn’t the same as power. Bigger capacity means you can have less valve timing overlap so a flatter torque curve and less variation in combustion quality through the rev range for a variable speed engine. Ideally, you want a 1 cylinder engine with a turbo to minimise wasted friction and exhaust gas heat, working at close to peak torque rpm. At a constant speed, the capacity is irrelevant within reason if it’s working at peak torque rpm. To ruin economy, add cylinders, throw heat out of the exhaust and have combustion as effective as a UN aid truck throwing bags of rice off a truck at a refugee camp. No auto gearboxes, no PAS, no aircon, no SUVs, live closer to your job, ideally use things called legs to walk to a bus stop where you meet and talk to neighbours instead of hiding in cars from people who support the wrong team , political party, religion or Nascar driver. Sorry, I’m English 🙂 Those hybrid electric cars are even worse than normal cars for the amount of pollution they cause in manufacture, transporting and refining the exotic minerals around the world. It’s like banning pedestrians from smoking on traffic-filled streets. Nobody needs more than 1000cc to transport one donkey/ass from home to work.

8 troy wiggins January 3, 2010 at 11:54 pm

terry, my 2006 chevy malibu automatic with k&n air filter ,partial front grill block and tires that 44 max are at 42 pounds gets me on the interstate about 42-45 driving 59-60 mph! my record on a 300 mile trip is 47.5 mpg’s

9 Terry Batws January 10, 2010 at 10:54 pm

Troy those Chevy Malibus are awesome cars and always get great gas millage. However it was not until the year 2008 that the E.P.A. started it’s long journey adjusting how they calculate miles per gallon to be a more realistic estimate of real life driving conditions, and these changes have already cost some cars 12% to 30% in worse E,P.A. Mileage Estimates. Your car is larger than mine and my subcompact Cobalt XFE (fairly rare, I have yet to see another one the road where I live) was a special model of Cobalt designed solely to get the very best millage of all subcompacts made in the same years.

I would love to own the car you have, but I believe your millage, if based on your dashboard’s computer, is like comparing apples to oranges when it comes to comparing such computed mileage to a post 2008 production model car because the EPA standards are much more difficult for a car maker to break the 40 MPG barrier with typical eternal combustion engine. Some companies had to shed a lot of weight just to get their new production models rated close to their previous year’s EPA estimate for driving.

As a matter of fact I have an uncle in Flint Michigan who retired from Chevy/General Motors. He too owns a Chevy Malibu, production year 2009 and he is happier than a tornado in a trailer park every time he calls to tell me he broke over 32 MPG again. He is proud to have his dashboard display 33 MPG with his automatic, but he claims he normally gets 29 to 31 MPG. It’s really great mileage when one considers the car is no small matchbox, and is more of a luxury model and far from being an “econo-box”. With each new production model I like them better!

For a more fair and updated comparison of true gas mileage, I would think a test between the 2011 Chevy Cruise (set to replace the 2010 Cobalt in mid-production 2010- EPA 40 MPG- stick OR automatic 6-speeds) and a 2011 Chevy Malibu would be most interesting as this will be a year in which the EPA will be even more tough (much more!) on how they estimate fuel consumption averages. Of course these EPA Mileage Estimates are before HYERMILING!! lol


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