Because the cars are just pasted into a scene, especially noticeable if you look at the Williams. Either that, or it has horrific AA and AF problems.
@Xero: I agree in some respects, but the lighting is off too... it's no better than GP4's lighting, and it's over-reflective too, like GP4's.
Looking at the Lotus 49, which obviously I know quite well having seen photo after photo, it's nothing like as detailed as the GPLEA's version in GPL, both models and texture.
I do like the track graphics though - always been a codies strong point.