I found some more free 3d car models here (3ds max file format)
They seem to be pretty good quality
Here is a Mercedes S55 that I rendered out.
I had to change quite a few of the materials to V-Ray materials, because the file comes with some standard 3ds max materials, but other than that the models are pretty good.
There is also a Nissan 350Z, Audi Q7, Honda S2000 and a bunch of other stuff