Dola -
Google is great. Here is a link to the official website which looks like it has some very cool features. My previous post was inaccurate, it is over 230 cars from over 60 manufacturers. They don't mention how many tracks there are. However, from the website it appears there are at least 32 tracks as you can click on their layouts.
http://www.xbox.com/assets/en-us/fla...te/default.htm