Live For Speed S2 is a serious racing simulator. No arcade modes, no steering aids - YOU have to do the driving. In S2 you can race alone or against the AI, but the real fun is to be found online, in multiplayer mode. Racing against real people is simply the best thing and LFS makes it easy for you to do so. There are also several online racing leagues you can take part in, if you are looking for something with a more competitive edge.
In Live For Speed you can also race off-road!