I quite like Nascar, started watching it a year ago. It's a bit like baseball, good when there's action, boring when there's no action. Overall it's nice to see drivers compete on almost identical cars and so on.
Also it's quite cheap. I've read a few articles about Nascar, also there's a sorta nascar car review on Jay Leno's website, basically, ready to race it costs 250.000$ for a car, plus a trailer for tools (also a tower for crewcheif) and 20-40 mechanics.
Only thing that bugs me is commercials, but you can tune in to ITV and ABR (german one), and there's almost no commercials at all, with original english commentary, with only commercial gaps filled by channel's own commentators.
Provlem with conventional non-oval racetracks, there's much less action, therefore much less attendance from fans and worse TV ratings, as it's much harder to overtake with their almost basic cars. If you look and Indy or Daytona, or even smaller one like Darlington, there's sitting room for 100k+ fans, which is good even for most F1 races, and it get's good TV ratings. The first qarter of the season on Fox gets about 13-17/21, 7-9 in the demo, depending on race start time, which is increadably good for 3hour mid-day (3-4-5-6pm) slot, and it still will be good for any primetime slot.
Basically it's cheap, entertaining and very profitable sport, with 36 (or 40 if you count all-star, and shows) races, 2-4 hrs each.