I saw one once. Truly impressive.
@raymond: I tought it was a standard SLS with some lights on the roof, 6-point seatbelt and more buttons on the cockpit.
The VLN layout is longer than the Tourist Nordschleife lap by ~30 sec.
Are you really sure of that? I am pretty sure they nearly complete the Nordschleife then run the short track which is at least 3km long. 30s to run 3km would be pretty fast.