Audi has committed itself to the DTM - the German Touring Car Championship - a touring car race series. But it's not just about fast cars - it's all about big business. The DTM'S first race in Germany happens in early May.In the weeks before the big event, there's a lot to do. Technicians and drivers have to be meticulously prepared and sponsors have to be satisfied. After all, Audi's involvement in racing is certainly not for charity. The firm hopes to win big - in both prestige and exposure. Report by Grit Hofmann and Philip Bilsky.