To me, including people in automotive photography is to help tell a story, to add more to a scene. With that in mind I will critique...
1) Mostly just a snapshot. Not much interest.
2)I think this is the best of the bunch. The lighting is very nice but the composition bothers me. There is too much space on the left and not enough on the right. It feels cut off.
3)Again, the composition feels cutoff and the background is very distracting which makes it feel like a snapshot. I would have tried to find a better angle to avoid the clutter.
4)Not bad. The trailers create a sort of leading line interest to compliment the man walking by. Better composed.
5)I think this one would have been the best, but the harsh shadow kills it for me. Not sure what you could have done about that... You are at a nice angle to the car with a tight crop but nothing is cut off as in the previous images. This does a better job of showing the entire scene.
6)This one is alright. Less background clutter. This is personal preference, but I don't like the "skinny" crop. I prefer photos to stay at a standard or 4x6 ratio.
Overall, there are some things you can do to make these more interesting. First, since there is motion in almost all, I would portray that with a slower shutter. Pan the car or particular person. Another thing you can do is get lower to the ground. It helps make things look less snapshot-like. Try different angles. Stand in front of the cars as they roll them toward you. Stand behind them. Try and think outside the box and don't be concerned if people look at you funny. Just don't get run over by a car. Hope this helps.