Car Wheels SINK into terrain and wont move forward

If you enter “showdebug vehicle” in the console, the engine will render the actual physx wheels. This might help you find out what’s wrong. If they are spawned, but at the wrong location, I’d suggest to make sure that the root bone transform is set to identity. UE4 has (had?) a bug that caused vehicles to fail if the root bone transform is not identity.