Is make a good generational update - that is, 10-15 more MPG and 10-15 more HP.

then the Prius matches the current generation of 2.0L sedans with mileage that nobody matches.

would more in both categories be better? of course! but even sticking to the simple formula above would mean the Prius can match or beat conventional sized competition in horsepower and mileage.... making the prius both a environmental and a "practical" choice