Racer is a racing car GAMING for Mac OS X. It provides professional driving physics for a realistic driving experience and an excellent render engine.
The game can be expanded with a variety of vehicles and routes. There are a great community this is on various websites.
Ambitious Tüfftler can also lend a hand and create cars and tracks. All this is possible by the good documentation.
Racer requires at least Mac OS X 10.3.9