There are 60+ cars for Sebring, only 30 for/from the WEC. There will be more cars that show up at each WEC race, the ACO/FIA had to put a cap on the number of WEC cars because WEC cars get an automatic invite to Le Man, and at Le Man they can't have more then 56 cars, so that's 27 spots open for invites outside of the WEC cars. Don't know who else listens to Radio Le Mans but those guys will have some live coverage of practice and qualifying, as well as the race. Check them out at radiolemans.com. They also have a weekly show covering all motorsports called Midweek Motorsports (F1, sports cars, IRL, NASCAR) it's on Wednesday at 18:00 GMT time, 3:00 EST (i think that's right). They are based in the UK and sometimes I don't get their humor but overall I really like the show.