Well, to answer B.R.'s question, the spacing is to scale, and the axles, center to center is right at 1 3/4", and the front on is 2 and 11/16". The smaller wheels are 33" in real life, and the larger front wheel is 42".
The only way I could use a powered truck for the back would mean I would have to cut a hole in the back or I find a motor truck that is skinny enough to fit the motor and the gearbox. I would have to have the truck about and inch or less in height, no more.
And one more thing, I may want to power the flywheel, so I ma at some point buy a small motor, like a small 1/2 long motor. But for know I just want to get the car moving.