Hi Adam, certainly no expert here myself but:
1. background is a bit and distracting attention away from the car itself.
2. is much better, although I might try and clone out the sign in the top right or crop it out, Also can you have a go at cloning the lighter line on the bonnet? Not sure what processing you applied to it either
3. now this one is my favourite by far of the whole series. nicely laid out and nothing distracting from the car.
4. again nice but think the processing might be a little harsh (just my personal opinion, sure some will love it)
One thing I noticed in all of them, did you use a circular polariser to try and combat the reflections in the paint? I know this is something I need to get for when I am using the 70-200
Phil