Technically yes, because the Nordschleiffe is officially a public 1 way toll road. That's why your car has to be insured, have MOT etc. But it could be that your insurance has ruled out the Nordschleife. Also, I have heard of a case where an insurer wouldn't accept the claim even though they did not exclude the ring in the conditions. But the insurer convinced the judge that the Nordschleife is not a normal road but a road that is on purpose made twisty and difficult to drive for racing purposes, because of which it could be qualified as a track. From what I understand the insurance did not had to pay.On a side night, on a tourist day are your guys' cars insured, if so how?