I have to say the first few shots are great apart from needing a bit of a brightness & contrast added to them. But as Driftnewb110 said the sun position is mostly in the same place all the time. Also I think you should experiment with different shutter speeds and focus spots, as in most your shots half the car is in focus and the other isn't giving the shots almost a empty feel. Try those few tips and you will improve. Also check out my gallery if you have time you get some inspiration from it.