Propeller-driven VW Beetle

My dad and his friend have been working on converting a glider with a small engine for gaining altitude from a gas to an electric propulsion system. To test the system that the’ve designed and built themselves, they have first mounted it on a classic VW Bug that weighs the same amount as their glider. This way, they can test the system under load while still on the ground! These guys are phenomenally skilled and know what they are doing. I wouldn’t try do this at home. I don’t think anyone else should ei