Yea any car will do with some upgrades. The competition is pretty bad. I on the other hand bought a Mercedes CLK DTM just for the event. I happened to see it the used car section and decided to buy it for 1.2 mil. Silly me.
I used the C63 AMG i won for competing in the AMG special event. With some tyres and basic exhaust it whips the competition. I've used it in the Expert 'Schwarzwald'(sp) event to with no problem, had a good tussle with the SLS on the 'Cape Ring', epic race.
You mean the german touring car championship right? the one with the strict list of german touring cars you are allowed to use? I used race mod lexus ISF, its the only dealer car you can buy to use for this championship it was not too bad, they are pretty quick the cars you race against.