Beakman explains how gas is explosive and causes the combustion engine in the car to work. He uses a model engine with a side view and demonstrates what is happening with the gasoline when it explodes to move the engine parts. Beakman shows how the engine allows the wheels to turn by relating it to riding a bike. Up and down motion of the pedals is converted to turning the wheels through the chain. Same in the car with the pistons turning gears and thus the wheels.