I keep coming back to your shots and I found some other things that need to be fixed. Granted I had to ask the opinion of my husband who is also a photographer, but here is what we figured out.
Your background is too deep and too busy. It is very distracting. The positioning of the camera is good because you can see part of the car and the model, but the light is too bright on her face, the background is too cluttered and the models positioning could be better, aka not so ridgid. RMT I thought I saw alittle bra in that one too!
In the 3rd shot, you need a different angle of the camera, you have a wide shot when it should be tall. You can see part of the car, part of her leg (which took me a minute to realize what it was), and if you are going to have part of the leg and the car in the photo you need more. And again the background is way too distracting, the lift in the background is way too noticable. So switch your view, and get more leg or even cut them off totally and this shot will be better.
#4 I agree is my least favorite shot also. You don't get a good representation of the shirts. Also they are standing in a shop that is cluttered with posters, lifts and other stuff that it takes away from the models. It also makes one wonder what the crap they are looking at. Like RMT said, are they at a funeral?
#5 works because the car is in the background with the other stuff. And so it kindof blends in.
If you want to use the car, put it in front of the garage door or just make the background black, then you will get better pictures.
You have great ideas, keep it up.