@ RookieBOB - a good effort, it just looks like you were plain and simple struggling for enough light.
Whilst the shutter speed (1/1250) is fine for freezing the action, your chosen aperture (f5.6) hasn't given enough depth of field to get the whole car from front to back in focus at that focal length. The effect can be quite pleasing so keep experimenting, only in this case it may have looked better if the front of the car, where all the dynamic stuff is happening, rather than the rear was in sharp focus.
Cropping in closer to the car would also get rid of that messy and distracting astro in the background. With a bit more practice and some more forgiving light you'll get the hang of it.
A few less dynamic shots from my weekend, had orders to leave the camera at home but ignored them...
