in all fairness for someone who is new to all this ive seen a hell of alot worse for (including my own). i like the color but i dont know what it is but something is bugging me about it :S. try adding just a little bit more contrast because it looks abit milky if that makes sense.
rims look good but id suggest re positioning the rear as its kinda squif. and dont forget if your changing the BG remember to take the old scene out of the windows and replace it with the new BG