HawkFanatic, the pics in that thread are cars that run in American Le Mans (ALMS) and Speed world Challenge. ALMS had the 12 hour at Sebring last weekend, World Challenge also ran that weekend as support races.
ALMS is running at Mid-Ohio July 20-22. Here's their schedule:
http://www.americanlemans.com/Schedule/SeasonSchedule.aspxALMS has Le Mans Prototypes and GT classes. Some of these guys will race at the 24 hours of Le Mans, which is by invitation only. The rest of the cars at Le Mans will come from the Le Mans class, which runs similar cars in Europe.
World Challenge will be at Mid-Ohio in July with them, support races again. World Challenge website is here:
http://www.world-challenge.com/They have GT (Vettes, Caddys, Vipers, Porsches) and TC (Acuras, BMWs, Mazdas).
Grand Am, which has the Rolex series (cars are Daytona Prototypes and GT cars) and the Koni Challenge (production based cars, very close racing, huge fields), which generally run the same weekend, but sometimes don't. (Note: Koni Challenge used to be Grand Am Cup). They're at Mid-Ohio in June.
http://www.grand-am.com/Home.aspThat's about it for production based professional road racing in the US. IF you get Speed Channel check out the Rolex race on Saturday and the World Chellenge GT and TC races on Sunday.
Jason