I've often wondered about converting a FWD vehicle such that one or both rear wheels could be driven. The rear suspension cage on at least 2 of the vehicles I've encountered would have enough room in and around for at least 5 HP under near the middle. (some only look like about 1 or 2 but it would be a start)
Lots of sprung weight which would need to balance in the middle perfectly which is bad but it looks like room can be made.
The pressing issue would be how to "drive" an unpowered dummy tag axle brake rotar?
On one of the cars it looks like there would be room to drive the rotor from the bottom with some style of friction wheel, hmm, maybe everyone is making things to complex.
A hybrid cobalt or antique insight with prius like abilty would be interesting
As for a RWD, there are 2 spline double ended motors around, sandwhich one in and VOILA.
Cheers
Ryan