CONCORD, N.C. — Tony Stewart believes he has an open-ended offer from Roger Penske to run the Indianapolis 500.

The three-time NASCAR champion turned down Penske’s offer in December to drive one of his cars at Indianapolis Motor Speedway, but Stewart revealed Monday he told “The Captain” over dinner he’d like to revisit the offer down the road.

“It’s a very flattering offer. I went back to Roger and actually had dinner with him in Indianapolis and told him he not necessarily backed me in a corner, but he made me a generous offer,” Stewart said. “I made him a counteroffer that it’s an open-ended invitation. So even though we haven’t accepted this year, maybe some year down the road we may be able to accept it. He never said no, so as far as I’m concerned we have an open invitation.”

Penske, a 15-time winner as a car owner of the Indy 500, first made his offer while accepting the Sprint Cup trophy and lauding Stewart, the 2011 champion.

“I know we took your spot this year,” Penske said. “But you’re a car owner, you’re a race driver, you’re a track promoter — how about doing the double at Indy this year? Are you available?”

Penske later insisted he was serious about wanting Stewart, an Indiana native and former IndyCar series champion, to drive for him in the 500.

Stewart, who grew up dreaming of winning the Indy 500, was silent about Penske’s offer for several days. Then he turned Penske down.

Sprint Unlimited

The format for the first NASCAR race of the year will be determined by race fans.

Fans will be able to vote on the length of the race segments, pit stops and how many cars will be eliminated after the second segment of the exhibition Sprint Unlimited scheduled for Feb. 16 at Daytona International Speedway.

The race was previously known as the Budweiser Shootout, and is the official kickoff for Speedweeks.

The lineup of 22 drivers will be comprised of 2012 pole winners and past Shootout champions. Fan can vote on NASCAR’s new mobile app or at NASCAR.com. Votes on the NASCAR Mobile ‘13 app will count twice.

IndyCar

IndyCar has changed the distances of four races in an effort to discourage fuel- mileage racing.

The announcement changes the lengths of races at St. Petersburg, Long Beach, Milwaukee and Mid-Ohio.