SuperTuxKart on Ubuntu Perfect Ten (10.10). It is the newest version, obtained by adding a PPA. The version in Central is a slightly older version with different interfaces.
Never played a game that actually includes some form of physics (except, well, Angry Birds). Keep in mind that the best game I've ever played is Red Alert. Two. The best FPS (probably the only) I've played is Serious Sam: Second Encounter. This one ran on a 945GM and combines random bloodiness with plain what-the-bleep fun (you have a headless guy screaming).
8/10 for "game", 9/10 for what it is.
Understanding that this is a clone of the Mario Kart, I am evaluating this on a stadard that is somewhat established on Mario Kart (Wii).
Lacks: Different vehicle profiles. All karts in Tux are (AFAIK) the same. In Mario Kart there are different handling and speeds. Loses 1 point.
Lacks: More power-ups (or power-downs). Personal thing (would be nice to have some homing stuff, but the cake is already somewhat homing, so). Loses 0.5 points.
Lacks: Slightly better graphics. Maybe a bit more details and please draw some bloom. But already better than the one in Central. Loses 0.5 points.
The whole "for what it is" is the potential factor, because I've seen vDrift (that draws bloom, filters anisotropy hence cannot run on my low-power computer).
But the game is free and open-source. So I should probably shut up.