[dumb_ricer]

Having played both Gran Turismo 3, Gran Turismo 4, and Forza a whole hell of a lot, I would have to say overall both of them are pretty damn good interpretations of how a car is in real life, pending tire choice. I would say once you get into the "Racing" tires, the realism kind of goes downhill in GT3/4.

Also, oversteer mechanics seem to be off in both games, with either being too twitchy and throttle dependant, or not enoughso.