Cars work by applying a rotational force to the road wheels. Using the friction between the rubber tyre and the road surface, the car is propelled in the selected direction of travel.
Almost all cars use an internal combustion engine based on the Otto cycle, harnessing the explosive power of a burning charge (air and atomised fuel) to push pistons connected to journals on a rotating shaft, and a selection of reduction gears to transfer power to a propeller shaft, and, via a differential gear unit, to the road wheels.
Some cars use an electric motor as an engine. These have not reached the maturity of development, and top speed, of traditionally fueled cars, but are more energy efficient and have negligible toxic emissions.
Cars generally include seats to convey the driver and, usually, at least one passenger. This is different to motorcycles, which have a saddle that the rider sits astride.