The Forza games are meant to be racing simulators, so they have a lot of options to make it a lot more realistic.
Apart from Forza 2, the only racing games that I played on the Xbox 360 are Burnout Paradise, Test Drive Unlimited and Sega Rally.
Sega Rally does have many different tracks. and cars, but it's an arcade racer.
Test Drive Unlimited is based on the island of Oahu, Hawaii and you can drive anywhere on the island. There are races and other events you can do around the island and the more you complete in first, the higher class rating you get and you unlock more races. There are many licenced cars that you can get from visiting different dealers, but some do have upgrades that are only upgrade packs, with the third one the best one.
Burnout Paradise is set in a large fictional city where every race and event always ends in one of I think eight different points in the city, and you have to improvise a route to get there (or follow the compass). All the cars are fictional and they have to be unlocked by either improving for licence for by finishing certain events. I think there are over 200 different events in the game.
