What kind of camera did you buy? Judging from the shadows, try to avoid shooting midday or mid-afternoon.
Your very first photo is the strongest because you framed the car in the corner which draws more attention to it. Just straighten the wheel next time.
The second one you could have turned the wheel towards the camera to focus on the actual rim itself. Nobody cares about what kind of tires you have
#3 is the samething. Make sure the wheels are completely straight or angled towards the camera so you don't look at tire tread. Also a slightly lower perspective may have been better.
The rest of the photos I can group into the same cateogory, don't cut off the car! lol. Unless your focusing on something specific (ie: Emblem, brand name of some sorts, something in particular) always keep the whole car/subject in the frame. #5 would've been very nice if the entire car was in the photo.
As an example on the wheel thing. In this photo that I took, the car's wheels are completely straight and makes the car have an aggressive stance. If the driver were to turn the wheels towards me you'd see nothing but tire and the car would look as if it was going in reverse or something. On a side note when I look at it I could've improved it by having him turn the wheels slightly to the right so the rims barely touch the body of the car itself in the photo.
Another example is this photo. Imagine if the front wheels were straightened out... wouldn't have a very good look to it right? It wouldn't really give the car that "I'm here" feel. It would just look like a boring parked car. (besides the crazy paint job right haha). Since the wheels are now turned they become the main focus along with the body of the car and everything flows together.