Originally Posted by dex37
OK, "nonsense" is maybe a too strong expression in this case, but still I would hate it if I have to do it. On track days here you usually have to wear a helmet, only during tourist rides at the Nürburgring you are allowed to drive without a helmet.
Outside the USA, they often allow people to drive on track with windows up.
Windows down is a safety regulation so they can easily pull people out of a car in case of emergency if the door gets stuck for any reason. Also, less chance of shattered glass everywhere if the window is down. The requirement for this is totally dependent on the track and track event operator. Almost always they will require this though.
At US autocross events, they allow people to drive with windows up. But that is at lower speeds and less chances of hitting walls and other cars.