Trackmania is a series I've known since childhood. It's a BRILLIANT series of racing games, one that spawned a whole new type of racing (sort of, I may be wrong for all I know). Head onto a MTA:SA race server and you will be greeted with tracks that bear resemblance with the TM style.
The game itself is epic, but you will need practice to get into racing properly. I've had years of practice, both on TM games and other, so it's not that difficult for me, but I see a lot of players who fail at cornering or falling of the "walls" and loops.
This is a game that will provide hours upon hours of competitive entertainment, there's a MLG style league for it as well. The ESWC was a competition held back in '06 that allowed players to win $10k!
At the end, the game is solid. You can mod vehicles, create your own tracks, so on. This is a game that will live off it's community. If the community dies, this game wouldn't be as great, because multiplayer is the place to be.
If you like racing, Speed-Racer style tracks, HotWheels perhaps?, then you'll like this game.
See you online! :)