[brucepick]

Mike,
Thanks! Tempting but... I don't know if I can get away.

I remember reading about Mike D's fifth wheel mod. I'm pretty sure he was the guy who did it. Can't remember though what car it was on, very possibly a Gen 1 Insight.

A small electric motor driving a wheel that (hydraulically?) dropped down somewhere in the center of the car, powered off a deep cycle battery pack. Put the regular drive train in neutral and it would run on straight electric on the highway, if I recall correctly. The benefit vs. powering the hybrid drive train off a large pack was the reduced mechanical and electrical losses due to (I think) a direct drive motor, so no losses from mechanical gearing and flexible shafts etc. etc.