I love rFactor, and I decided I missed it on the Mac.  Turns out, it wasn't hard to wrap with CXEx, which is the replacement for CXZ, which is based on TransGaming and Wine's wrapper stuff... etc. etc.

The Configuration app will set resolution, fullscreen, etc.  I haven't tested it on nVIDIA cards, but it works fine on ATI.

I'll do my best to seed but if you have any issues with this after downloading you're pretty much on your own...