I have to say that the new artist is a good idea to start in only a few changes (wheels, lowering, door handles and logos away etc ..) The basics first!
Then ontopic
Whole Volt is a very poor quality. You have taken a car from a small picture and then enlarged it to fit a new background. Netcarshow to find every picture at least 1600x1200 size. Do not start on a small image to make, because the accuracy will suffer.
The car has begun to change in the right direction!