but i have,like this
I thought you were asking for help to resolve a graphical error, because no offence, but that looks hideous. Maybe the car is alright (if a little... chrome plated), but why the hell is there so much motion blur and bloom? It looks like a terrible attempt to ripoff the graphical style of gta4, but they stopped halfway.
If someone were to actually increase the appearance of the cars, they would need
realistic reflections, and dynamic damage (if that's the word for it), you know dents appearing in the car and such. But that's probably impossible.