Allmendinger: NASCAR is hardest

The relative dearth of technology also seems to have morphed from detriment to draw for open-wheel drivers accustomed to cars capable of precision steering at 20,000 rpms and laden with telemetry that tells engineers how to adjust the cars. Computer-aided data acquisition is banned by NASCAR, and its ill-handling cars have internal combustion engines employing mechanisms dating to the 1950s.

It puts a heavier emphasis on driver feedback, and Franchitti and Villeneuve relish the challenge.

"I never liked getting to a track and the team telling me, 'We don't want to hear what you think, just drive,' " Villeneuve says.

Wheeler says he's noticed the shift in philosophy after hearing open-wheel drivers deride NASCAR as "racing taxi cabs" since attending his first Indy 500 in 1964.

"The car was totally unsophisticated then and still is, but it's supposed to be," Wheeler says. "It's made to entertain fans, not engineers. It's come full circle with people realizing that racing has got to be entertaining."

Allmendinger says he wasn't derided by his Champ Car peers for making the move.

"They all said if you get the opportunity to go and don't, you're an idiot," he says. "There may not be as much technology, but they're the hardest frickin' cars I've ever driven in my life. They're difficult beasts to hang onto."

Allmendinger has qualified for 14 of 31 races as a Cup rookie, joining a long roster of recent Indy car winners who have met with limited success in adapting to NASCAR. The only recent exceptions have been two-time champion Tony Stewart and Montoya.

Evernham cautions that "everyone is saying, 'Wow these open-wheel guys can do it,' but Juan Pablo is special and they need not underestimate he's got way more talent than everyone realizes."

"I'm not saying that other guys can't do it," Mears says. "But in Juan, you're looking at the guy who was most capable of doing it as quickly as he did. It's probably not the best gauge." USA Today