I only watch ADAC Masters occasionally or VLN races the the Nürburgring, but never saw a Mustang there.
guess they are only driving in that European Championship series which I never heard of.
Audi R8s, the Vettes and the Alpina B6s usually are at the first few places.
Andreas Wirth, the 2nd driver of the first Alpina B6 GT3 is a customer at the dealer my brother works at (BMW and Alpina), nice guy, awesome car.