So far the best V8 supercar game I've played is the V8 Challenge mod for F1 Challenge '99-02.
Check it out here
V8 Gaming.
You can also create your own cars, and get the latest skins. (Big bonus especially when you want to race the current cars). There's a whole forum here:
RSC V8 Forum. This is made by the same people who are making the RFactor V8 Supercar mod.