The study of the behavior of the airflow as it passes around a moving object and the forces exerted by the air on the object. In car design the positive and negative lift of the airflow is studied in wind tunnels.
Negative lift is preferred to press the vehicle closer to the ground.
Car air resistance is also studied. Also called automatic gearbox. Operation can be electrical or hydraulic. Today many of the engine-driven auxiliaries use belt drives. The diameter of a gasoline or steam reciprocating engine cylinder.