A must have for Xbox only gamers but for those with a PS2 there is a better choice.
First of all, there are two things that Forza does better than GT4: Tire to pavement physics and collision detection. GT4 lags behind in those two areas as well as suffering from noticeable ‘screen shake’ and bumper car AI. However, overall, Forza still falls far short of Gran Turismo 4.
With regards to the tire physics, GT4 handles very realistically, especially with ‘Economy’ sim tires equipped. However there is still two much of a sliding on ice feel when the car loosens up and when driving a rear wheel drive car, the rear end doesn’t break away as convincingly as it should. By comparison, the same car in Forza will loosen up under acceleration (from a standing start as well as in corners) with very believable physics.
Everyone complains of there being no damage model in GT4 but of more importance is the complete lack of any collision detection. In GT4, when cars collide with each other, or with trackside objects, they merely bounce off like a pinball. Forza has fantastic collision physics and contact of any kind results in a very realistic result. Add to that an adequate damage model (visual and performance based) and Forza beats GT4 in that department hands down.
However, a low frame rate is Forza’s Achilles Heel. The game runs at approximately half the frame rate of GT4 and cornering is where this becomes most apparent. With only 30 or so frames a second to work with, the turning in Forza has a notched, jerky feel that is no where near as smooth as GT4. Moreover, the weight transfer modeling is inadequate. Sometimes the weight transfer in GT4 is too pronounced, but in Forza it is almost nonexistent, with cars exhibiting almost no body roll or nose diving under heavy braking and cornering.
Other Forza shortcomings worth mentioning include are inaccurate car models that are not as well scaled as in GT4, clunky, stiff menus and an overall low resolution appearance. Also of note is the in game audio where engine sounds are seem muted and the two available bumper cam views which are too low to the ground. If you do not own a PS2 then Forza is the best driving game you can buy, however, if you have a PS2, I would suggest sticking with GT4.