DTM 15, ADAC 14, GT3, ADAC13, Sihouettes, Audi TT, Formula RaceRoom, Aquilla Class. There might be more but that's all I can remember.
All of the cars are a constant work in progress and subject to improvement over time. The GTR2 class received an update around february of 2015 as I recall. When talking about the "new" updated physics, people are generally referring to the physics improvements from summer 2015 which started with the GT3 cars. Those updates were helped in development from Kelvin van der Linde and some other real world drivers. The cars do feel a bit different than the GTR2 cars, but that is part of the fun, they handle differently. Perhaps sometime in the future they will be looked at again and further improved from where they are now.