Then there's the traffic - given the microscopic margin for error involved in laps that lead to times such as the one above, a simple lift due to a potential encounter with another car is enough to ruin one's stopwach performance.
In fact, Touristenfahrten rules strickly forbid the use of timing equipment in the car, with this measure being aimed at reducing accidents.
Oh, and le's not forget the fact that one needs perfect knowledge of the infamous German track in order to avoid the traps that its corners are for Ring novices.
So, how close can you get to the 6:47 in real life? Well, the piece of footage at the bottom of the page delivers a respectable answer.
The video brings us a 7:04 lap on the smaller BTG version of the Nordschleife, with the feat having been recorded during a recent Manthey Racing track day - this is a Porsche-owned racing team that also modifies street-legal Zuffenhausen machines, among others.
A performance driving instructor sits behind the wheel, while the owner of the GT2 RS rides shotgun.
Of course, things can get even spicier than this. For instance, just earlier today we talked about the GT2 RS owner having received a passenger lap in the 2019 Porsche 911 GT3 RS during the said event. And with Porsche works driver Kevin Estre at the wheel, the 520 hp beast delivered a 6:50 BTG lap.