Speed Dreams is a 3d cross-platform, open source motorsport simulation and racing game. It is released under the GNU General Public License (GPL). For the moment, the supported platforms are Linux (x86, x86_64) and 32 bit Windows. The Mac OS X port is 95% finished.

Get the linux and possibly mac versions at the Official Site. The game is supported by Desura.

Visit the Official Site (more tracks and cars)

Features:
– Over 30 unique car models spanning five classes of competition
– Three all-new car classes; World Rally, LS-GT1, and LS-GT2
– Graphical updates for many original TORCS tracks
– Two all-new circuits; Brondehach and Goldstone Sand
– Skilled and intelligent AI drivers; fight down to the last meter of track
– 23 detailed circuits; ranging from fantastic originals to replications of real-world circuits to the best of original TORCS
– All-new Career Mode; battle your way up from boring production cars to powerful world-class racing machines
– Network play; show your friends who is BOSS