Lovely sunstar on the rear window of the first car. M<y favorite is the #65 car. What do I think? Mostly too much top space, too much that's visually competing with the car and track in most of these; the Firebird, the 33 car...the parking area and the green porta potty. Porta potty...no...that's just not a good vantage point to set up, same with shot #1, with the bleachers on the grassy knoll (OMG--was that a shot? Or just a backfire?), the grassy knoll and the empty bleachers distract from the car. On the other hand--if say, this was a race, and there were 150 people in those bleachers--then yes, that might have actually worked great. Lots of people in different, colored, bright shirts makes for a good streaky backdrop effect; horizontal aluminum bleachers on plain, green grass is not good, and the sky is the nail in the coffin.
THe way I see it, a panning shot needs the kind of background that LOOKS GOOD SMEARED, and of this set, the #65 car and the white outbuildings work the best...not a great shot, but better than some of the other backdrops.
The #43 car, for example--a GOOD, and LOGICAL background, and a decent place to set the camera up! Needs more contrast IMHO, but not a bad shot. Again, that area is a good example of the kind of backdrop that WILL/.COULD/SHOULD look good when shown smeared, or streaky; the exact opposite is the red car, with those annoying signs and that big $ sign...that just robs all attention from the car.