Neil, Mech is probably "planning" on using his own engine design as the powerplant, connected to another one configured as a hydraulic pump, and one on each wheel.
http://ecomodder.com/forum/showthrea...ign-11517.html
Which, it should be noted, is all very untested and theoretical, and thus still has some outstanding questions. But is also the subject of his patent application, which of course isn't proof of much of anything useful to a non-mech.