Diffuser (automotive)

The trailing or leading edge of a diffuser may receive a nolder—a precise small lip, protuberance or wing to enhance its performance.

Front diffusers also exist (especially on Le Mans Prototypes or similar cars); however, they generate downforce purely from momentum exchange with the air, as there is nothing ahead of them to drive.

When the driver lifts off the throttle, the exhaust flow is greatly reduced, which makes the diffuser less effective, robbing the vehicle of downforce.

In addition to creating downforce, the front wing and nose try to keep "clean air" flowing around, and more importantly under, the car.

[3] Clean air under the car prevents flow separation from occurring in the diffuser, which would severely rob its performance.

This wing's profile is used to drive the diffuser, creating that low pressure area to help move air from the underbody.

[4] Conversely, equal downforce levels could be attained for significantly reduced drag with this "Red Baron" wing.

The culprit was the so-called double-decker diffuser introduced at first by Brawn GP, WilliamsF1, and Toyota Racing, but later put into use by every team.

In most closed-wheel race cars, the underside of the splitter smoothly integrates with the undertray, creating one large flat plane that is driven by the rear diffuser.

Some race cars, such as the Toyota GT-One, use an additional diffuser immediately behind the splitter to help create more downforce.