A spoiler is a kind of wing that is mounted on the rear of the car in a horizontal position. Its function is to provide high-speed stability. In most cars, the spoiler is purely cosmetic, as a car has to be going over 100 mph to take advantage of the aerodynamics of the spoiler. Some mini-vans also make use of a spoiler, but it's upside down, and angled. This type of a rear spoiler only keeps the rain off the rear window.
Spoilers generally work by disrupting the airflow going over a car. This disruption has two primary effects:
- reducing the amount of lift naturally generated by the shape of the car, and
- increasing the amount of positive pressure downward through the vehicle
The result of these two effects is the same: increasing the force between the tire and the road surface, thereby increasing traction. This increase in traction allows a vehicle in motion to brake, turn, and accelerate more aggressively without tire slippage. Additionally, this is accompanied by an increase in aerodynamic drag.
In nearly all cases, downforce and drag increase as the speed of the vehicle increases. Thus, spoilers that are effective at very low speeds often generate excessive drag at high speeds, and spoilers that work well at high speeds are often ineffective while moving slowly. Some spoilers have adjustable components so they can be tuned. Formula One cars, for instance, feature different settings so the car can be optimized for short, low-speed tracks or larger, high-speed ones.
Types of spoilers
Although the most recognizable spoiler is the wing spoiler, there are actually many different types of spoilers.
- A wing spoiler is an airfoil is suspended above the body of the vehicle.
- A lid spoiler (commonly trunk lid spoiler, lip spoiler, or boot lid spoiler) is often a ridge of plastic or metal attached directly to the top of the trunk lid.
- A roof spoiler is a small ridge of plastic or metal attached to the very back of the roof, usually just above the rear window.
- A splitter is a spoiler attached to the front bumper, very close to the road surface, sometimes known as a "front spoiler" or on stock or stock-appearing cars as an "air dam."