Well... ok... but the Nordschleife is used minimumly ten times a year as a Race track for endurance races. And you can only drive on the Nordschleife when it's opened. The opening times are on the Nürburgring page. It's normally not opened the whole day, only a few houres. The rest of the day the track can be booked by a "Driving Training Group" or by BMW, Mercedes and so on. As test track.