http://gtchannel.com brings you a new documentary called "Racing at the 24 Hours of Nürburgring" by Polyphony Digital, the producers of the Gran Turismo games. Watch the full 3 part documentary here on GTChannel. The German Nürburgring Circuit is also known by many as the "Green Hell," as it is widely considered the most difficult track in the world. Every May, over 200 cars participate in the grueling "Nürburgring 24 hour race" event here, the world's largest touring car event.