The entire engine system can be likened to a massive air-pump, or the respiratory system in a human being. Air from the environment is drawn in, does its work, and is expelled. In a human body, work is done when oxygen is being drawn into the lungs. In an engine, this same oxygen is used to support the combustion of fuel, gasoline in this particular study, and this combustion in turn generates energy that drives the output of the engine, through the transmission system, and to the wheels that propel the race car.