Oh gawd........
If anyone here has actually owned or driven the first gen insight you would know the least of the hybrid system you use and more lean burn the better your mpg is and we are talking triple digits here.
The Prius drivetrain is designed hand in hand to the prius car. Didnt anyone see the article about putting 17 inch rims and aftermarket tires FUBARing the mpg of the prius as is?
Now the engine maybe something as it is a 4 valve per cylinder, but its a 13 to 1 compression unless you use the same electronics and cam that leaves the intake valve partly open to reduce pumping losses for that atkins cycle efect.