Open source racing game with a track editor. It focuses on closed rally tracks with possible stunt elements (jumps, loops, pipes). You can drive in Single-Player mode racing against the clock or completing championships. There is also an online Multi-Player mode.
It's nowhere near perfect.
But it's a GREAT timewaster. I love drifing around corners when I have five or ten minutes to waste. Racing against my ghost is just an added bonus.
I'm giving it a 10 because it's a lot of fun for what it is - a simple, fun, arcade rally game.
The physics aren't perfect, neither are the cars, but it's still a lot of fun - and it's actually quite challenging at some points!