Aye Veeate.
Dunno if the top part of the paintjob is supposed to be black, or chameleon-ish, but either way it looks kinda odd.
If you were going for black, try out this awesome tutorial by Greboth. It's one of the best out there.
For chameleon, I have no idea
You could darken the front mesh a bit, and add some shadow by: Selecting the mesh, pick up a soft brush, make it quite large, and then brush from the distance. OR, lower the opacity of the brush.
Next up is the rims... I'll hand out another useful tutorial, this time by Photoshopper. Try following it, and you should achieve a much nicer result.

Take care,

Nick