Although this is not a game, it does allow you to take part in multi-player races over a local network.
One of the main aims of Racer is to involve users in its development, and building circuits or creating cars is far easier than in other driving simulators. Racer can easily integrate models created in ZModeler, 3D Studio or Maya.
Another interesting feature in Racer is its in game physics. It draws from the real life movements of vehicles by analyzing the logs of applications such as MatLab program.
Although the simulator only contains a single track and vehicle (a spectacular Lamborghini), you can visit the Racer website for details on how to download new racing cars and tracks for the program.