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More is less: larger 1.8 liter engine saves gas by running at lower rpms with more torque. (http://www.nytimes.com/2009/01/14/automobiles/autoshow/toyota-prius.html)

http://www.youtube.com/v/totyPle98Rs&color1=0xb1b1b1&color2=0xcfcfcf&feature=player_embedded&fs=1
Rex Roy - New York Times – Jan 13, 2009

See for yourself -- Ed.

IS IT REAL? Absolutely.

WHAT THEY SAID The midsize third-generation 2010 Prius will offer better mileage, enhanced performance and innovative design features than the outgoing car. It will be quieter, roomier, and equipped with advanced standard and optional features, including a moonroof with solar panels, four driving modes, Intelligent Parking Assist and steering-wheel touch controls that display on the instrument panel display.

WHAT THEY DIDN’T SAY Our hybrid is better than Honda’s, but based on the mileage numbers, they could have. Honda also used the Detroit show for the introduction and first public display of its production 2010...http://www.nytimes.com/2009/01/14/automobiles/autoshow/toyota-prius.html

Using a larger engine and getting better FE isn't really a new thing. I have had several experiences in the past where the same vehicles with different engine sizes would get better FE with the larger engine choice.

The Prius III with an 1.8L engine ends up with a higher EPA than Prius II with 1.5L, but PIII also has exhaust recirc amongst other ICE efficiency upgrades. It's not an apple to apple comparison of engine size.

One might argue and say "who cares", but there is added cost and complexity added to the new generation. Personally, I would favor EGR in a 1.5L package. Rumors are flying that Europe may get the FE economy upgrades and keep the smaller engine. We'll see.

Hi All,

The 1.8 might not be a good PandG engine. Its got more rotational momentum, which is overhead on the pulse, which requires a glide to a more traffic unfriendly lower speed to recover. A 1.5 three cylinder engine with a Turbo would be the best of both worlds. But Turbo's are maintenance issues. A Turbo would need to be a water cooled bearing, with its own lubrication loop, and probably need to have Hybrid Bearings, to last reasonbly similarily to the rest of the Prius. They could have left out the Turbo in the Prius, and put a Turbo 1.5 into the Corollas, Matrix and Scions. But instead those cars use the new 1.8 that is also in the new Prius. So, their economy of scale is with the 1.8 liter. Which is my opinion of why they really did it. Remember the 1.8 has the smaller pistons, which can rev higher, which is not important for a Prius, but is for the other cars. Otherwise they would be quite power starved during highway ramp maneuvers.

My opinion on the highway fuel economy claim, is that they figured out how to automate SHM. And if they could have done that with the 1.5 liter, it would do better. But the control of SHM with the smaller 1.5 liter engine is on the hairy unstable edge. Its proably going to be allot easier with the 1.8. Too bad I do not get a chance to drive at highways speeds, even when I am on the highyway around here.

They took out the complexity of the coolant heat recovery system. And added in the complexity of the exhaust gas heat recovery system. As there is more heat in the exhaust than leaks through to the coolant, this is a good thing for mileage. Especially in winter, when you only get your one shot of 16 C water on a 10 F morning with the present system. But the exhaust pumps out similar heat over and over as you drive the car. So, there is more heat to be harvested into mileage with the new system. The only concern I have is if its possible to make this system durable, and/or fail tolerant (just loose a little mileage, but the car keeps working otherwise). At this point, it looks like a even level of complexity between the too, but more cost (materials and longer plumbing runs) for the new system.

They also took out the fuel tank bladder. The goals for that were noble, but they ended up with a horrendously complicated gas tank, and were not able to get rid of the fuel vapor recovery system. So the bladder does not synergize out complexity of the standard system, like one would expect it could. And, it results in uneven fill-ups with temperature which work against the car gaining acceptance. So, the bladder appears to have been ahead of its time due to lack of good materials for it. Eliminating the bladder reduces the complexity, too. But safety is reduced when there is a collision without the bladder. too.

Does anyone know where they ended up on the AT-PZEV scale? Teir 2 Bin??

Looks like a home run for Toyota. It is the first time in a several decades that I am considering something other than a Honda for my next car.

Honda fell short of the mark, IMHO, with the new Insight. Nice car, but a combined rating of 41 mpg, lower than my Civic, is not where I want to go.

Frank

Does anyone know where they ended up on the AT-PZEV scale? Teir 2 Bin??

Looks like a home run for Toyota. It is the first time in a several decades that I am considering something other than a Honda for my next car.

Honda fell short of the mark, IMHO, with the new Insight. Nice car, but a combined rating of 41 mpg, lower than my Civic, is not where I want to go.

Frank
According to the information I saw, the Prius ended up at Teir 2 BIN 3.