RARS is the Robot Auto Racing Simulation, a competition for programmers and an on-going challenge for practicioners of Artificial Intelligence and real-time adaptive optimal control. It consists of a simulation of the physics of cars racing on a track, a graphic display of the race, and a separate control program (robot "driver") for each car. All RARS software and activities are free and open to the public. Currently only Windows and Unix versions are actively supported, but some old DOS and OS/2 code exists and it should be possible to get it back to work.
There has been no RARS competition for a long time. If you are interested to participate in simulated car races, then you can take a look at the TORCS Racing Board.