Actually, If you want to play a perfect driving simulator try ferrari f355, It was a game dedicated to driving a competition ferrari, there was only 2 cars to drive, the original and the race version. If you play this and then play any other game, you can see where the flaws come up. Personally I liked the ferrari alot, and still have it, but could never really get into it, due to the fact I really don't like ferraris, sure if someone gave me one I'd take it, but even if I could afford 100 of them I wouldn't buy one. I just like to drive a car that is not made to be a race car, and treat it like one. now a g35 coupe...
But you are right forza looks great, and guess what, if you had a hard time figuring out what game those pics were from, like I did, That is great, that means graphically GT4 is on par with the best looking Xbox racer. And if microsoft has anything to do with it, I would be identical to the best racing games they compare it to.
just some trivia, But microsoft has a keen eye for seeing what works, and emulates that into whatever project they want to achieve, look at the controller, look at the games they have, shoot look at windows, do you think MS came up with GUI or even encryption... nope, they are rip offs. So if you think about it forza should play as well as gt3, should look better, will have customization like nfsU, online play is a given, and from what I have played, similar physics to f355. Just don't excpect to hop into this game and start winning races, the cars you can drive, seem to have an exaggerated power curve, and tend to torque out from a dead stop, and braking is not one of those things you can do all on or all off, you have to feather the brakes, something that I truely missed from gt3, from a dead stop I could just floor it and I would go straight, except when I was in the grass, in which case I would be looking at the ass end of the cart.