i *THINK* he means that instead of your standard motor per wheel setup, you could instead go with something like 2 huge motors, powering the wheels through a differential? Like your car, the two drive wheels are powered by ONE power source, but split via a diff. If so, he wants to split it between front right, rear right, and front left, rear left.
If that is what you are saying, I can understand what your thinking.. to save space you would only need 2 motors. Perhaps set in the middle of the 4 tires.
Is that what you meant?