...often many of you forget about the macro function.
I agree with this. Macro can be used on many car photos, and is very handy regardless what you might shoot.
Using some macro on these shots.
Again, more macro, especially useful on the emblems or L-Plates.
But, even more important, is lighting. Where this picture didn't turn out amazing, because of lighting. Now, a reflector, or light flash would make it better.. (I couldn't move the car, and there was a truck on the other side.) Also, this is an example of getting down to shoot the car, so it's not a plain eye-level shot.
When you shoot into the light.. Sometimes it looks ok; as long as the hood, roof or windows aren't blinding the shot, but other wise no. This one is debatable, if you're going for a sort-of sleeper look.
And, for photography, this is my favorite example I've got uploaded. Not many reflections of other cars, planted in the middle of the frame, good lighting to your back, wheel turned, showing back wheel, and background easily worked with in PhotoShop. My only issue, is, it's eye-level, if I had gotten down lower, it would be a much more dramatic shot.