When a vehicle moves at high speed it pushes air ahead of it and leaves a turbulent low-pressure zone behind. A trailing car entering that zone experiences less frontal air resistance and can therefore maintain the same speed with less engine output, or accelerate beyond what its engine alone could sustain in clean air. The lead car benefits slightly as well: the following car pushes a wedge of higher-pressure air forward that reduces the drag created by the lead car's rear spoiler or diffuser, allowing both to run faster as a unit.
At oval tracks, the effect is largest at superspeedways where cars reach their highest absolute speeds and where aerodynamic forces dominate the power budget. The faster the cars travel, the greater the drag penalty they carry, and the greater the gain from removing part of that penalty through drafting. The handling consequences are significant: the leading car loses rear downforce while retaining normal front downforce, while the trailing car loses front downforce but retains rear downforce. A car sandwiched between two others loses downforce at both ends simultaneously.
Drafting was identified as a race-winning strategy in stock car racing during the 1960 Daytona 500, when Junior Johnson discovered that his Chevrolet, which could not match the outright speed of the other cars, could sustain competitive pace by running directly behind them and using their slipstream. Johnson won the race, and drivers across the sport began experimenting with the tactic systematically.
In IndyCar racing, the phenomenon is present on all superspeedways and was long understood as an inherent feature of oval competition. Drivers who fell behind the leaders on a long oval could use the draft of the pack to regain ground in a way that was impossible on a road course.
On NASCAR's restrictor-plate superspeedways at Talladega and Daytona, where intake restrictors reduce available horsepower substantially, drafting effects are at their most extreme. With insufficient power to break away from a partner once the draft is broken, passing became closely intertwined with cooperation between drivers. The "slingshot pass," in which a trailing car uses accumulated momentum in the draft to emerge with a speed advantage at the end of a straight and complete the pass, became a signature maneuver of superspeedway racing.
Bump drafting, in which a following car physically contacts the rear of the lead car and pushes it forward to maintain momentum, became common at Talladega and Daytona. Done smoothly in the right location, it helps both cars sustain maximum speed. Done roughly or near a turn, it can destabilize the lead car and cause spectacular multi-car crashes, a recurring feature of superspeedway racing events. NASCAR has introduced buffer zones and other restrictions to limit dangerous bump drafting.
Tandem drafting, in which two cars lock bumper-to-bumper and drive as a unit for extended distances including through corners, emerged as a distinct strategy at Daytona when Kyle Busch and Ryan Newman demonstrated at a test session that the combination ran roughly fifteen miles per hour faster than single cars. Tandem drafting dominated the 2011 Daytona 500 before rule changes ended the practice by modifying car aerodynamics.
A refinement of the technique, side-drafting involves one car pulling alongside another and using its body to direct airflow away from the lead car's side, creating a drag increase on that car without requiring a full pass to be completed. It became a particularly useful tool at restrictor-plate tracks after bump drafting restrictions made conventional slingshot passes harder to execute, allowing drivers to disrupt a competitor's aerodynamic balance without making contact.
In open-wheel racing, including the IndyCar Series, slipstreaming on long straights is a primary overtaking tool. A trailing car can close a gap to the car ahead using the draft and attempt to pass either before the braking zone or on the straight itself if a speed advantage exists. The technique is more complicated on the faster oval sections because the "dirty" turbulent air behind a leading car in a corner reduces the aerodynamic grip available to the trailing car through its wings, making close following particularly difficult through the banked turns that define superspeedway layouts.
Drafting mechanics are modeled in sim racing titles that simulate oval or high-speed circuits. Accurate aerodynamic wake simulation requires each car's drag coefficient to be recalculated dynamically based on the proximity and relative positions of surrounding cars. In titles with high-fidelity physics, drivers can exploit the draft for lap time gains in multi-car situations on superspeedways in the same way their real counterparts do, and the handling imbalances caused by losing downforce while running nose-to-tail are reproduced as a driving challenge that must be managed through setup and technique.