Also, I think a regular car engine does not work upside down. It might be okay for the short amount of time, but not any longer.
Something to do with the fuel deliverance and lubrication, I'd imagine.
In the battle of Britain, German Bf-109s would often escape from combat by quickly diving, whereas the Spitfires often facing them would need to roll over onto their back prior to diving(inverted); the Spits, having carburated fuel delivery, relied on gravity to keep the float bowls full where the Messerschmidt's motors were fuel-injected and would continue to run in negative-G conditions.
The ad, while perhaps *possible* IMO looks WAAAY too smooth to be real.

