I've been hooked on the muliplayer (when I can find a match), because there's a game variant called playground that consist of:
King - In which one person is the king, and all other racers try to crash into him to become the king in closed enviromments - so can't run very far.
Cat and Mouse - where there's a randomly chosen slow car for each team, while all other racers get 2 classes higher. Mouses job is to cross the finish line, and the cats are supposed to try and protect or stop the other mouse.
Infected - Point is to avoid be crashed into (like King), but the winner is that who stays avoid becoming infected in a small enviroment.
It's a shame more people are playing online, it's so much fun.