We certainly used to have the 2L class as well as the V8 class.
The Astra V8 Coupé and the Audi TT V8 were interesting looking beasts.
As I said, I haven't followed motorsport for at least 4 years. The Mustangs might have been from the time before I moved to Germany, although I thought they were there in 2002... And Opel were still competing, when I lasted watched a race.

I think that a lot of the German drivers tend to compete more in the European and World Touring Car Championship, as opposed to the national level, I certainly remember seeing S2000 class cars racing on German circuits with German drivers in the mix, but it could have been the Euro or World championship...