okay, i know, as well as you guys.. that you cant put "special" bricks down on the grid and make them drive able/movable. so why not make some sort of GUI where you can select the front, back, sides, extras, wheels, and mounting points (note: these parts being premade for whacky vehicle combos) then save it, boom! its a vehicle... then you can load it like any other vehicle via wrench.
p.s. now if you've ever played any of the lego racer games you know what im talking about.