The driving game FOSS scene is quite healthy. With actively developed games like VDrift, SuperTuxKart and Ultmiate Stunts, and relatively complete games like ManiaDrive, Stunt Playground, and Torcs, there's quite a decent choice. But there is always room for more! :-)
Motorsport aims to become the most "realistic simulation of wheeled vehicles". It's been going since 2003 so there's a lot of development history and it looks like it's got a bright future with several consistent developers moving it forward. It is unclear whether this will end up as a racing game or a stunts game or maybe just a generic driving game, but it looks fascinating and has lofty goals.
Stunts 2005 is a fan remake of the classic Stunts game from yester-year. To be fair, a lot of the FOSS driving games seem to take inspiration from Stunts aka 4D Sports Driving. Anyway, Stunts 2005 comes with it's own level editor but development seems to have halted after the initial release. Since I can't play it here I can't make any observation on how complete the game is.
Also worth noting is that the SuperTuxKart guys are working on another release that will include updated AI among other things, although updated physics I think are being pushed back to a subsequent release.
Blah blah blah holiday. :-)