Well first of all , you need antialiasing . go to your NVIDIA Control panel or AMD Radeon settings (witch GPU u use ) and change the Anti aliasing to like a 8x or 4x , the best looking is 16x but i recommend you to use higher resolution and AA set to x8 (depends the power of ur gpu because this game is very laggy :s )
Another tip is to use good ENV-Maps (if you dont know how to change the env maps , pm me and il show you how)
The point of ENV Maps are the car reflections , witch i consider them the most important aspect of the game .
Here are some links witch i consider them the best
V V V V V *LINK* *LINK* *LINK*
And.. thats like it
(+++ You can use ENBs that use Ambient Occlusion witch makes some good shades)