Rollout or rollout allowance in North-American

drag racing Drag racing is a type of motor racing in which automobiles or motorcycles compete, usually two at a time, to be first to cross a set finish line. The race follows a short, straight course from a standing start over a measured distance, most c ...

is the difference between actual acceleration time and measured acceleration time. For the published

0 to 60 mph The time it takes a vehicle to accelerate from 0 to 60 miles per hour (0 to 97 km/h or 0 to 27 m/s), often said just "zero to sixty", is a commonly used performance measure for automotive acceleration in the United States and the ...

acceleration time in North America, a

rolling start A rolling start is one of two modes of initiating or restarting an auto race; the other mode is the standing start. In a rolling start, the cars are ordered on the track and are led on a certain number of laps (parade or caution laps) at a pre-det ...

is used, beginning after the initial

standing start A standing start is a type of start in auto racing events, in which cars are stationary when the race begins (different to the rolling start, where cars are paced). Procedure In a standing start, cars are completely still but with their engines ...

position. The method approximates the behaviour of

dragstrip A dragstrip is a facility for conducting automobile and motorcycle acceleration events such as drag racing. Although a quarter mile (1320 feet, 402 m) is the best known measure for a drag track, many tracks are eighth mile (201&n ...

measurement equipment for 1/4 mile racing, which was historically limited to only recording after the vehicle had passed over a start line. This leads to a 0.2–0.3-second apparent difference, with larger

wheel size The wheel size for a motor vehicle or similar wheel has a number of parameters. Units The millimetre is most commonly used to specify dimensions in modern production, but marketing of wheel sizes towards customers is still sometimes done with ...

s giving a larger

exaggeration Exaggeration is the representation of something as more extreme or dramatic than it really is. Exaggeration may occur intentionally or unintentionally. Exaggeration can be a rhetorical device or figure of speech. It may be used to evoke str ...

in timing.

History

Historically acceleration measurement took place using dragstrip equipment placed over a measured

distance Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...

, with a light gate at the start and end. These light gates measured the point in time at which a vehicle passed the measurement point, rather than the point at which movement (acceleration) first occurred leading to a slightly faster apparent time.

Standardization

With the advent of on-board measurement via

Global Positioning System The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...

timing, the North-American car magazines sought to standardise the precise measurements and to account for the historical difference in a way that was consistent between publications, and still comparable to existing published measurements for older vehicles made via traditional light gates. The result was the standardization of a "1 foot rollout llowance (30 cm) derived by accurately measuring a complete acceleration run, then subtracting the time taken for the first of vehicle movement, with only the derived timing being published.

History

Standardization

Further reading