The swap with Montoya was Jeff Gordon, who was rumored to be set for a longer more extensive "test" but quelled the rumor last week. The next American F1 driver would logically come from open wheeled racing, but who knows!?
Glenn
OH, and Lwin, they're not "circles". In addition a number of the "ovals" have different banking, etc at each end of the oval. Track lengths vary, as do the top speeds, including the superspeedways where restrictor plates prevent them from hitting over 200MPH. Fact is that it's not a situation where you just hold the steering wheel and stomp the throttle. The modern Cup cars are turning 11,000 rpm's with around 850HP. This is not your "father's NASCAR"!
Personally I love to see them road race at courses like Infineon(Sears Point) and Watkins Glen.