Glossary: Spoiler

A spoiler is a device attached to an automobile whose purpose is to ’spoil’ unfavorable air movement across a body of a vehicle, when it is in motion. This can result in improved vehicle stability by decreasing lift (force pushing the car upwards when in motion) or decreasing drag (force pushing the car in a direction opposite to that of its motion) that may cause undesirable handling in a car at high speeds. Some spoilers are fixed on cars primarily for looks and styling purposes which have little or no aerodynamic benefit. In some cases, an improper after market spoiler might interfere with the car’s aerodynamics resulting in a decrease in the vehicle’s performance in terms of mileage and stability.

The main aim of a spoiler in passenger vehicles is to increase fuel efficiency and reduce drag. Vehicles can be fixed with both front and rear spoilers. Front spoilers, found beneath the bumper, are used to direct air flow away from the tires to the underbody where the drag coefficient is less. Rear spoilers, which modify the transition in shape between the roof and the rear/the trunk and the rear, act to minimize the turbulence (flow of air which is chaotic in nature) at the rear of the vehicle.

Spoilers meant for racing cars also work on the same principle of disrupting the airflow over a moving vehicle. This disruption’s primary purpose is to reduce the amount of lift naturally generated by the shape of the vehicle while it is moving and to increase the contact between the tire and the road surface, thereby increasing traction (road grip). The increase in traction improves the stability of the vehicle when turning, braking or acceleration. Spoilers of this kind which increase downforce are majorly used in racing cars where road grip is essential.