I was at the Pocono 500 race on 06-08-2008 to work at a souvenir stand as part of a fund raiser. I'm not much of a NASCAR fan, so I've never been to a race before. I figured I might as well get some video while I'm there, so here ya go.
Once the race is up to speed, I was fooling with different shutter speeds. At first, the shutter is very fast (1/2000 or 1/1000). As each lap passed, I ratcheted the shutter speed down a notch. You'll notice the effect of the speed of the cars changes with each lap.
Recorded with my Canon HG10 with an external mic.