A spoiler is designed to "spoil" unfavorable air movement throughout the body of an automobile in motion. They function by disrupting or diffusing the airflow that passes over and around a vehicle as it passes over the vehicle. Diffusion is accomplished by increasing the amount of turbulence that flows over the shape, "spoiling" the laminar flow, thus providing a cushion for the laminar boundary layer. A lot of times spoilers are added to a vehicle for styling purposes rather than practical ones. They are often fitted to high performance racing or sports cars.