Driving and Racing

GLtron
gltron is a last player riding game based on the light cycle portion of the movie Tron. (C) [Mac OS X, Mac OS 9 (unsupported), Linux, Windows] [GPL]
http://www.gltron.org/index.php

TORCS - The Open Racing Car Simulator
3D racing simulator using OpenGL technologies, derived from RARS. Players can develop their own driver using C or C++. (C++) [Linux, FreeBSD, Windows] [GPL2]
http://torcs.sourceforge.net/

TORCS Power Smart
An additional car for TORCS, The Open Racing Car Simulator. Specs: Smart ForTwo, 180hp, 156mph (250km/h). Licensed under the Free Art License 1.3
http://donnar.webng.com

Tux Racer
An Open Source project in which the user takes the form of Tux (the Linux Mascot) and races downhill through alpine trails.
http://tuxracer.sourceforge.net

VDrift
Open source driving simulation made with drift racing in mind, powered by Vamos physics engine. (C++) [Linux, FreeBSD, Mac OS X and Windows (Cygwin)] [GPL2]
http://vdrift.net/