Q3Rally is a car driving and car combat standalone game. It is based on Ioquake3. Since the latest release (available at 20/08/18) also MacOS X (10.5 and above) is supported. Also Windows and Linux (x86/x64). Try it out. It's damn fast, baby.
A really nice and original idea. Add a racing mod to the Q3.
The problem present on this game could be the single player gaming, and some bugs presents on the maps and gameplay. So that is why mi final score is not too high.
Buth if you wanna get fun experimanting with this, play some races on DeFRaG maps (fully insane)