What if there were room, and not too heavy and "maybe" tooth belt driven ? Perhaps field input could be regulated by brake line pressure ? Might help cars with less than adequate braking, on the rear ? This system could also,"unload" for maximum accelleration, ie. act like more stall in a torque convertor. More Hz with less brake dust. roverman.
As long as you're thinking along these lines, think about putting the alternator behind the engine. I've seen prototypes where it was built into the engine flywheel assembly. Alternatively, I suppose it could be external, but run off the ring gear or even moved to the rear axle or to a transaxle.
Several years ago there was a lot of buzz about moving from 12V to 24V or even higher. With higher voltage, wiring (and motors, etc.) can be downsized since less electrical current is required to achieve equal work. 24V would be relatively convenient (compared to 36V or 48V or ...) since it's used all around the world - except North America - for heavy duty truck electrical systems.
Keeping it on the engine, it could be used to increase launch velocity,(loaded/un-loaded). Building into the flywheel should increase potential for output ? roverman.