A good set. My personal favourites are 1 & 16 as they are composed to show more of the dust trail being left behind so they invoke the sense of speed quite well. In respect to the shutter speed, I'd agree maybe a little too fast, but it's the age old balancing of blur in the right places vs blur in the wrong places
I would tend to crop image 16 a little tigher above the car/dust cloud to remove some of the bank. I think that would really make the image pop.
On a side note, how much dust did you have to remove from your kit after the event