Centered, is rarely best, try to use the "Rule of thirds" and place the car in one cross-section of a tic-tac-toe board
Make sure your horizontal lines are even
Make sure the wheels are facing the camera to make the photo a little more interesting
Here's a quote from a photography friend, "The background is not just noise – While the car is going to be the subject of your photo, that doesn’t mean that the background doesn’t matter. Even with proper composition, a good background can substantially help or wreck a photo. Industrial backgrounds are very overused, but it’s understandable to use if you’re in a pinch. Ideally, you want a background that helps add to the theme of a photo or just plain looks good overall. A driveway photo shoot isn’t all that great either unless the driveway is filled with a bunch more nice cars. Just be careful not to choose a background that blends in too much with your car, because then your subject won’t stand out."
Make sure nothing is "popping" out of the car