Originally Posted by Speedster159
Car racing, circuit sprint, and drifting...
I heard rFactor is good?
Drifting, LFS is the best for that - huge community even on the demo. Lots of interesting servers too, not just for racing but cruise servers, along with drifting and autocross.
Depending on the cars you want will change the game you should get. If you want touring cars, Race 07 + expansions are the way to go for that. If you want something not that realistic but with a lot of different addon tracks and cars then rFactor is a good option. If you want something continually progressing and with the highest level of realism then you'll want iRacing.
Race 07 has decent enough AI and a lot of people racing it online. rFactor has a bit worse AI and a lot of people online, although you'll need the correct mod and track to race. iRacing doesn't have AI but has properly sanctioned online racing series.