Interesting capture. Unfortunately, I think you were the victim of your camera's slow shutter speed. The 1/20 second exposure definitely gives you a sense of speed by blurring the cars closest to the camera, but because it's so difficult to hand-hold any camera for that long, the cars at the end of the pack aren't as sharp as they could be.
A common technique for this type of capture is panning, that is following the action with the camera to achieve a sharp subject (in this case a car or cars) against a background of linear blue.
Just my $00.02 worth - your milage may vary.