Algodoo

Yeah this is the same method I used on a truck, main problem is that a pair of wheels cause hideous lag issues (bogged down my sim 50%) Add ABS (the obvious addition if you'll use these, of course) and you'll need a quantum computer

BTW, would you like to join algo.boards.net? There's almost no activity there but we guess it'll get better eventually. Only thing I ask is if you can upload your best scenes there (not really upload: get the scene number from Algobox, and use the tags [scene]number[/scene] and it will display a dialog with the direct download and a link to the description), then ask others if they want to join.