The aerodynamic function of a NASCAR race car or truck can dramatically impact competition on the sport's fastest tracks. It can also make teammates out of unlikely rivals seeking an advantage.
The process of "drafting" has been in practice since the superspeedway boom of the 1960s, when it was discovered that two cars moving in close nose-to-tail formation could cut through the air easier than one car by itself. The mutually beneficial partnership reduces the amount of turbulent ("dirty") air around multiple cars, allowing all cars in the draft to make small but important gains in speed.
Even 50 years later, the use of the aerodynamic slipstream is still an important facet of high-speed competition.