The TAG Heuer Pit Stop Challenge is a pit stop contest held during activities leading up to the Indianapolis 500. Since 1977, the event has been held on Carb Day, following the final practice session. As many as twelve top teams in the field compete in a single-elimination, tournament-style competition, two teams at a time. Under the current rules format, during each heat, two cars line up side-by-side in a specially-constructed pit lane, which resembles a drag racing layout. The cars go from a standing start, and race into the pit box. Pit crews must change four tires and hook-up a dummy fuel hose to simulate a refuel. The driver races out of the pit box to cross a finish line, which is a couple hundred feet down the lane. The time is taken from the drop of the green flag to the crossing