How Impound Races Work

Impound Race Allowances


After the qualifying race and inspection, the crewmembers are required to put the car into the garage while under the watchful eye of a NASCAR official. The two crewmembers that are permitted to remain in the garage are allowed to:

  • Turn off the master power switch and other electrical switches
  • Take out the radio
  • Check tire pressure
  • Place a cover over the car

When those actions are complete, the two crewmembers must leave the garage and close up shop. On race day, two crewmembers are allowed back into the garage so long as a NASCAR official accompanies them. The crewmembers are then able to:

  • Connect the oil heater (though any generators used must remain outside the garage)
  • Open the hood
  • Prime the oil system
  • Turn on the car
  • Remove the car from the garage
  • Open the oil cooler bypass valve if necessary
  • Start the engine
  • Close the hood
  • Check and set the tire pressure
  • Tighten the wheels
  • Put the radio back inside the car
  • Put in a water bottle
  • Remove or repair tape on front of car
  • Replace equipment batteries under NASCAR supervision

NASCAR also has strict limits on the amount of fuel that can be added to a car:

  • Two gallons of fuel can be added if the track is one mile long or less
  • If the track is one and a half miles long, three gallons of fuel can be added
  • If the track is more than one and a half miles, up to four gallons of fuel can be added
  • At no time can more than three crewmembers accompany a car to the fuel pumps -- and the crewmembers must be accompanied by a NASCAR official


If you would like to learn more about NASCAR racing and related topics, visit the links below.

Related HowStuffWorks Articles


  • Shinzawa, Fluto. "Gentlemen, don't change your engines". The Boston Globe. (Accessed 01/12/09)
  • Siska, Ellen. "The ins and outs of impound races." (accessed 01/12/09)
  • Waltrip, Darrell. "New spoiler spoils good racing but impound rule works." Fox Sports. (accessed 01/12/09)
  • Warren, Hollis. "What Really Grinds My Gears: NASCAR's Impound Rule" (accessed 01/12/09)