Full laps (flying or standing start) cannot be timed on public days as there are access gates and speed restrictions on the last straight. Public day times are for a shorter lap of 19.1 km from Bridge to Gantry (BTG).

Full laps can only be timed on a closed track with the restrictions on the long straight removed. Please read below for exact Sport Auto track length. It is 20.6 km (a full lap is 20.832 km)


from Wikepedia: http://en.wikipedia.org/wiki/Nordschleife_fastest_lap_times

Track lengths and timing

Not all of the following laptimes are comparable. The complete de:Nordschleife is 20.832 km long, full uninterrupted flying laps can only be done in closed sessions and race events like Castrol-Haugg-Cup.
During the industry testing sessions in which de:Sport auto records its "Supertest", the track can not be traveled at full speed past "Tribüne 13" (T13, grandstand 13) in order to allow safe access from the old exit/entrance there. Thus, Sportauto Supertests cover only about 20.6 km, which in average yields a 7 s shorter lap time compared to a full lap.
There are 5 sections on the 20,600 meters long Supertest-Nordschleife:
1st=3850 m
2nd=4235 m
3rd=4825 m
4th=4846 m
5th=2844 m
=20600 m