Most teams are using lower power radios... Not likely to be more than 2 or 5 watts max. Being UHF, outside of a couple miles, you're not likely to receive very much if anything. The track's communications (which most people don't really care about) might be going through a repeater... NASCAR's might also.
There are plenty of frequency lists for the race teams, NASCAR, and the media (PRN/MRN Radio, Fox/SPEED, etc.) that converge at the track. I will usually program primary and secondary frequencies into my scanner, but it's rare that any team is using their secondary frequency, much less a third or fourth.
Here's just one of the better lists freely available...
2013 Nascar Sprint Cup Scanner Frequencies
Also note that that list is only for the Cup teams... not the truck or Nationwide series.