I got the Abt Audi TT-R Touring Car '02 as a random free car; I dont remember if it wasnumber of miles, cars in garage, or completed expert series, though. I put some racing softs, and it absolutely blew the competition away in that event; no skill required.
The first german touring car that passed in the used dealership for me when I had to do this event was the BMW M3 GTR race car. modded it (you can increase the engine output) and changed the oil ( around 660 BHP total after all that). put on racing softs and no other car in the field could touch me.
Favourite John Marston quote: You'll be the first to know when I kill you.