The car engine burns fuel to convert chemical energy into kinetic energy (motion) and thermal energy, following the First Law of Thermodynamics (energy transformation).
Combustion releases the chemical energy held in gasoline in an automobile engine. This chemical reaction generates hot gases that expand and push the pistons inside the engine. As the pistons move, they provide energy to the crankshaft, spinning it and moving the vehicle forward. During this process, the energy does not vanish; rather, it transforms from chemical energy in the fuel to mechanical energy in the engine, with some heat energy as a consequence.
This energy transformation is consistent with the First Law of Thermodynamics, which stipulates that energy is conserved—it is never created nor destroyed, but just transferred from one form to another. The chemical energy of the fuel is converted into the kinetic and thermal energy of the vehicle. Thus, the car engine offers as a practical example of this fundamental law in action.