Sprint Cup Series

Race speeds vary widely based on the track. The fastest track is Talladega Superspeedway where the record race average speed is 188.354 mph (303.126 km/h) with the record qualifying lap of 212.809 mph (342.483 km/h) set by Bill Elliott in 1987- this was never beaten because for 1988 onwards engine restrictors were made mandatory to reduce speeds after several serious accidents.

The slowest tracks are Sonoma Raceway, a road course, with a record race average speed of only 81 mph (130 km/h) (roughly 1:18.444 seconds) and qualifying lap of 99 mph (159 km/h) (roughly 1:12.364 seconds); and Martinsville Speedway, a short, nearly flat "paper clip" shaped oval, with a record race average speed of 82 mph (132 km/h) (roughly 23.093 seconds) and a qualifying lap of also only 99 mph (159 km/h) (roughly 19.127 seconds).

The average speed is figured out based upon the winner's race time throughout the entire race, from the waving of the green flag to the waving of the checkered flag, including laps spent under caution, divided by the distance of the race.

Time elapsed during red flag periods is not added into the calculation of the average speed.

See also:

Piston Cup

Race speeds vary widely based on the track. The fastest track is Talladega Superspeedway where the record race average speed is 188.354 mph (303.126 km/h) with the record qualifying lap of 212.809 mph (342.483 km/h) set by Bill Elliott in 1987- this was never beaten because for 1988 onwards engine restrictors were made mandatory to reduce speeds after several serious accidents.

The slowest tracks are Sonoma Raceway, a road course, with a record race average speed of only 81 mph (130 km/h) (roughly 1:18.444 seconds) and qualifying lap of 99 mph (159 km/h) (roughly 1:12.364 seconds); and Martinsville Speedway, a short, nearly flat "paper clip" shaped oval, with a record race average speed of 82 mph (132 km/h) (roughly 23.093 seconds) and a qualifying lap of also only 99 mph (159 km/h) (roughly 19.127 seconds).

The average speed is figured out based upon the winner's race time throughout the entire race, from the waving of the green flag to the waving of the checkered flag, including laps spent under caution, divided by the distance of the race.

Time elapsed during red flag periods is not added into the calculation of the average speed.

(Source: Wikipedia)