Forza does have everything you listed, though the new one's online feature is awful atm. As was said, it's not the best simulation-racing game out there, but it certainly does simulation better than most games. It has different difficulty settings you can use to make driving more or less realistic, but it doesn't seem to effect the AI. The AI's probably the most unrealistic thing in the game though, cause they're seemingly unaffected by the laws of physics at higher difficulties.
Do it right and the performance on both of those can be just about the same...
However, the one on top is an RPG magnet. Drive that out of your garage on even a moderatly full server and you're getting hosed.
Back in my day the only cars we tuned were hot wheels.
However, the one on top is an RPG magnet. Drive that out of your garage on even a moderatly full server and you're getting hosed.