"did you protect somehow the microphone?" Yes, on the one hand i prefer omni - mics, which are less sensitive for wind in general. On the other hand I used a simple foam windshield and pulled socks over them. Furthermore the wind was not so strong as it sounds like - it was almost at midnight.
...I'm working in a piece that try to explain the dialog that now days exists between industry and nature. your file is good ! I know how difficult is to have a clear sound when you have all this air around.
Nuerburgring is too far for me to visit, but I can drive the Nordschleife on the PlayStation at home. I choose my Honda Civic and it takes more than 20 minutes(!) to go only one lap. Anyway, it describes the atmosphere of the racing track well.