I agree with gimp, post a bigger image, and read up on a good tutorial on how to rednder/colour cars, ill give u a link to were i learned how to do it i have only ever done one but there is another one coming but from this tutorial i have learned a lot
Good luck with your next attempts but im sure if u follow this tutorial you will be producing some great work
<A HREF="http://donbenni.deviantart.com/art/Vector-Tutorial-v2-16419597">Tutorial</A>