Very nice set of photos.
Autocross is one of the more difficult car 'action' shots. When you use a fast shutter speed you 'freeze' the wheel/tire and make the car look standing still, unless you get it with some body roll, even then you still what to get the wheels with some blurr. If you pan the camera then you blur the cones. You did get one good panning shot with the cones blurred in the background, nice shot shows location.
Very good set of images

you should post them on the photo website I told you about.
BTW What camera/lens are you using?
Later,