here's what i think...
1st shot.. wheel should be straightened..the black roof is underexposed..The lighting is just overall bad in that pic, shadows are too strong.. You have a tree and a lamp post growing out of the car.. that should be avoided
2nd shot, roof under exposed.. but overall my fav shot of your set.. BUT I think it would have been a killer shot if you would have somehow gotten the whole christmas tree in it..
3rd pic no real complaints except watch what's in your background growing out of the car..
fourth pic.. cropped too close for my tastes.. the light in the background is distracting too and looks like a second antenna :P
5th pic.. wheel turned wrong way.. background is not very nice.. underexposed top..
overall, I think the composition and background is a little bit boring in many of the pics.. if you are going to do a real nice photoshoot, plan ahead and find a location that is not distracting and compliments the car.. the christmas tree idea was nice though... In all of those pics, the car is right in the middle of the photograph.. makes it appear snapshot-ish.. experiment with your framing..
--mike