If you look and study all the different videos, you'll find that almost all the times recorded on the Nordschleife, the finish line (or stop clock) is different from the start line. Here's good explanation as to why:
Track lengths and timing
Not all of the following lap times are comparable. A full lap of the Nordschleife, bypassing the modern GP track, is 20.832 km (12.944 mi) long. Most laps are completed 200 metres (656 ft) shorter for safety reasons. 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 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, sport auto Supertests cover only about 20.6 km (12.8 mi), which in average yields a 7 s shorter lap time compared to a full lap.
There are 5 sections on the 20,600 m (68,000 ft) long Supertest-Nordschleife:
* The first is 3,850 m (2.4 mi)
* The second is 4,235 m (2.6 mi)
* The third is 4,825 m (3.0 mi)
* The fourth is 4,846 m (3.0 mi)
* The fifth is 2,844 m (1.8 mi)
* The total is 20,600 m (12.800 mi)
Some lap times are even claimed to have been done during tourist driving sessions. Because it is forbidden to race on tourist days as it is very dangerous to drive fast among the general traffic one should not try to measure the lap time on a tourist day. As the full main straight cannot be driven at speed due to the modern exit/entrance there, these laps are usually timed "bridge to gantry", which is only 19.1 km (11.9 mi) and thus about 30 seconds shorter. Additionally, there are two speed limits (one in Breitscheid, and one on "Doettinger Hoehe") on tourist days, which also impacts the lap time.
