This game loves telling you it's the ultimate driving simulator. To quote Flava Flav: DON'T BELIEVE THE HYPE!
That being said, I used to LOVE Gran Turismo 2 and 3, but that was before I'd driven real racing cars and found out how they REALLY handle. Polyphony seems to think that to make a game more realistic, you have to make the cars almost undrivable, and as far away from realistic as possible... Wait. Isn't that... a paradox? I believe it is! Driving a racing spec'ed car in Gran Turismo is NOTHING LIKE driving a racing spec'ed car in reality. Avoid this game AT ALL COSTS. If you want a closer representation of real racing, go buy GRID, which is not a simulation, but at least it doesn't do false advertising, claiming they do the ultimate driving sim. What GRID is, however, is much much more of a realistic driving-experience than GT.
To give another example of how bad the GT physics engine is: My old Pug 205GTi had LESS suspension travel than the ingame Ferrari F40, which is widely famous (or infamous) for it's stiff ride! How does that make sense? I believe that Polyphony thinks realism only means pretty graphics, because that's the only strong point of Gran Turismo, because it does indeed look amazing. But there are so many other driving games that looks GREAT, but has much more "realistic" driving physics than GT.
To conclude this review, I have to say: Stay away from Gran Turismo!