Make a steering linkage, an engine, drive shaft or chain, brakes, seats, grabbable handles so the user can push or pull or attach horses or cattle to pull
Im hoping it would be possible ro build vehicles by craftable components. Eg make wooden wheels and axles you can place just like other 3d building exept make them moveable you could place wheels on to axles. place wood beams to make a frame. Maybe attach the front axle via a pin in the center to make it steerable. Attach a drawbar to hit h to a horse