Forza Motorsport 2 is a the only simulation-based Racing title on the Xbox. While it does have it's share of flaws, the game is very ambitious. While it may not be the most exciting racing title, maybe arcade racing has more glitz and glamor, Forza is an earnest attempt at grass roots racing.
There are many types of vehicles to choose from and unlike competitor Gran Turismo, the customization is more similar to a Need for Speed game. With that kind of customization, the possibilities of making a completely unique car is simple. Engine swaps have to be one of the most interesting aspects of car building.
And of course, there is the multiplayer. If you enjoy dirty, nose-grinding races, strap in for Forza Motorsport.