I wrote:
I see your point. But the Prius ICE is 70 HP (52 kW), so it is the same. The ICE is small, too. Much smaller than a regular engine. It is 34% efficient. I doubt the Wankel is much better than that.
The Prius ICE is derived from an earlier conventional Otto cycle Toyota engine. Even if a Wankel would be better in some ways, there is much to be said for using an off-the-shelf proven engine. This goes back to what I said yesterday about manufacturing thousands of DC3s in 1940, instead of trying to update the design.
Imagine a time when millions of plug-in Prius cars are on the road, saving hundreds of millions of gallons of gasoline, and racking up millions of hours of experience with advanced batteries, control system, repairs, safety and so on. With that experience under our belt, it might be a good time to introduce a more radical Wankel serial hybrid design. This would also be a good time to introduce other radical changes to the automobile, such carbon filament materials for the body and hydrogen powered motors. Bringing out these improvements one at a time over a 5 or 10 year period would probably work better than trying to introduce them all at one time in something like an exotic "concept" car.
All of these improvements will multiply together to reduce consumption. They do not add up; they multiply: if a light carbon body and a hybrid engine configuration both reduce consumption by by half, a vehicle combining both consumes only one fourth as much petroleum fuel as a conventional vehicle. As Shultz and Woolsey wrote:
"The effects of these policies are multiplicative. All should be pursued since it is impossible to predict which will be fully successful or at what pace, even though all are today either beginning commercial production or are nearly to that point. The battery development for plug-in hybrids is of substantial importance and should for the time being replace the current r&d emphasis on automotive hydrogen fuel cells."
http://autos.groups.yahoo.com/group/calcars-news/message/68 - Jed
