Here are some of my favs from a recent rally here all shot with 40d and sigma 100-300 f4 except wide shot with swift thats a sigma 24-70
more at my flickr http://www.flickr.com/photos/33183532@N00/
#1. #4 my fav. but with this kind of head on shots it is hard to show the speed of the cars so they just look like they are standing still. Unless of cos they are in the air as in 1 and 4. pretty good photos none the less. It would be more interesting if you show some photos in different angles.
PS the last one i really like but it was just a more too off focus
thanks for comments, thing is i almost always shoot high aperture and low shutter speeds to get alot movement but for this even i wanted to get theses types of DOF shots as I had always wanted to try them, so I like the results, I used to alot panning shots have tons form local track meets and rallies