<human>:  How does a car engine work?
<bot>: A car engine works by converting energy from a fuel source, usually gasoline, into mechanical energy. This energy is then used to power the car's wheels, thus propelling the vehicle. Inside the engine, this energy is created by a series of controlled explosions created by the ignition of the fuel-air mixture in the cylinders. This is done by using pistons to compress and ignite the fuel-air mixture and release the exploding energy, causing the pistons to move and the crankshaft to rotate. This motion is what powers the car and moves it forward.