Drag coefficient - definition


Drag coefficient (commonly denoted as Cd) quantifies the resistance of a vehicle as it travels through the air. A lower drag coefficient indicates a car will have less aerodynamic drag, but the drag coefficient is always associated with a particular surface area, so it's not directly comparable between cars of different types.

Aerodynamic drag increases with the square of speed, which means that it's increasing crucial to acceleration and fuel efficiency at higher speeds.

Mounting optional non-factory equipment such as roof racks, mud flaps, spoilers and bike racks can alter the drag coefficient.