Torque Motor

From RC-Autopilot Wiki

Torque motor

Another idea would be to mount the differential directly into the hollow shaft of a torque motor. This is the differential removed from the original Microcar gearbox, it has an outside diameter of 85mm and a total length of about 18cm.

There is then plenty of room to put a motor of 40-45cm outside diameter directly in the drive shaft of the car.