ADAC Rennen is a touring car and GT endurance racing event held in Germany comprising over 25 km (15.5 mi).
The car racing event is participated in by more than 200 cars, and over 700 drivers around the world.
The event was introduced in 1970 by the ADAC as a real race, unlike the earlier endurance contests that covered 12h, 24h (in 1961 and 1967), 36h, 84h and even 96h, like the Marathon de la Route.
Just like the VLN series with its 4 hour races, the 24h race is mainly aimed at amateurs, in order to fill a starting field of around 200 cars. Unlike the VLN races, the 24h is officially an international event, with bilingual (German and English) organization, paper work etc.
For each car, an entry fee of 4508 EUR (as per 2010) has to be paid, plus 3000 EUR in advance for fuel.
Typical entries range from second hand standard road cars to European Touring Car Championship vehicles and GT3 sports cars like the Porsche 911 GT3.
The participation of manufactures and professional teams and drivers has varied over the decades.
As spectator numbers had dropped in the 1990s when only rather standard FIA Group N cars competed, more spectatular vehicles were admitted since 1999, like the Zakspeed Chrysler Viper GTS-R which originally was built by Oreca to FIA GT2-spec, turbo-charged Porsche, modified Deutsche Tourenwagen Masters cars from Opel and Abt Sportsline-Audi, and the Schnitzer Motorsport-entered BMW M3 GTR V8 that had been run in the 2001 American Le Mans Series.
Due to various changes and versions of the Grand Prix Strecke, the overall length of the track varied from the original 22.835 km (14.189 mi) to nearly 26 km (16.2 mi) of the maximum length configuration which was in use in 2002 and 2003, after the GP track had been extended by the Mercedes Arena.
As this section and its large paved run-off areas was useful as extra paddock zone for the competitors of the support races, it is bypassed with a sharp Z-shape chicane since 2005 for a 25.3 km (15.7 mi) track length.
For practice, 230 cars are allowed, 210 qualify for the race, driven by 800 or more drivers, as 2, 3 or 4 can share a car. One driver is allowed to drive 150 minutes nonstop, and can enter on two cars, yet a rest time of at least 2 hours has to be observed between two turns.
