As I stated in a previous thread on the same topic (yes, believe it or not someone posted this before), You could prove this by simply mounting wheels on the top of a small aircraft. Put the aircraft in a large tunnel, fly the aircraft to the top of the tunnel and see if the aircraft "drives" on the top of the tunnel. As I stated in yet another thread on the topic; Can a Formula 1 car drive upside-down? yeah, sure, when airplanes fly!