Roof flap

A roof flap is an aerodynamic feature of modern race cars, especially stock cars.

The roof flaps serve as a situational spoiler. A race car's body is designed to optimize downforce, but if that body is spun so air is flowing in reverse, lift is generated instead of countered. The roof flaps' job is to disrupt that airflow and prevent lift.

The decision to implement a safety device to keep cars on the ground came after a crash involving NASCAR Nextel Cup driver Rusty Wallace, where his car was spun around and lifted off the ground. The car landed in a grassy area of the track and his car tumbled violently down the frontstretch.

One noticeable use of roof flaps is in the Pixar animated film "Cars". During the climactic race, Lightning McQueen is spun around, and shown with his roof flaps opened. Merchandise featuring McQueen also often depicts the roof flaps (unless a feature of the toy is placed on the roof itself).