Bob - You have some nice panning shots there! When taking shots from the stands, I try to use a slow enough shutter speed (125-500/second) and pan with the car so the background is very blurred. Your shots look good.
I don't know what you did in the photo editing software to the images other than cropping? It doesn't look like you messed with color, contrast, sharpening, etc.. That is good, in my mind. I hate it when people mess with colors and bump up contrast and create unnatural colors. The vehicle's colors should look the same in the picture as they do in real life, not brighter or more colorful, but exactly the same. Again, it doesn't look like you did this, so good for you!
If there are any professional photographers (do it for a living) lurking, they can correct me if I am wrong, but I believe that they are required to submit their files directly from their camera to the media companies. No modifications allowed whatsoever. I would guess that this insures that the image is exactly as taken and not modified for color, to add or remove things, etc... Sounds fair to me.
When I get back from shooting hundreds of images at the track, the only modifications I tend to make are in cropping. Besides the fact that it would take hours upon hours to attempt to "fix" each image, I believe in leaving them as I took them, again with the exception of cropping.
Just my two cents...