How about just having a controller per wheel. Then adding a simple (or complex) throttle pre-conditioner circuit. The pre-conditioner would take input from speed sensors on each wheel as well as the main throttle input.
It could generate 4 throttle signals, one for each of the controllers.
The pre-conditioner could be a simple traction control type set up for regular cars and something much more complex for racing situations.
It may also be able to compensate for controller/motor failures.
Switch between 4 wheel drive and 2 wheel drive.
If there is regeneration available it may also be able to use that to give even more control.
With the addition of some accelerometers and gyroscopes it could be heading into the realm of stability control.
Also for reliability, using a throttle pre-conditioner may mean that if it ever failed it could be bypassed and the throttle directly feed the 4 throttles. You wouldn't have all the nice traction/stability control type features but at least you could drive home.
It would also mean standard controllers for whatever type of motor could be used.
Just a thought.
