They're just as comfortable strolling through Gasoline Alley.
While Newman, David Letterman and Joe Gibbs have long had ties to racing, more and more American celebrities are getting involved in the sport. Everyone from actors to Hall-of-Fame athletes to world champion boxers is joining the ranks.
"I like it because there are no critics, no lawyers, no agents," said Priestley, a heartthrob on "Beverly Hills 90210" and now a co-owner of Rubicon Race Team. "You go out and compete, it's black and white."
In a sport where names mean everything, the addition of outside "stars" has created a different look for racing.
Gibbs, the former Washington Redskins coach, and former Dallas quarterback Troy Aikman each won three Super Bowls and are now listed among NASCAR team owners. Letterman, Dempsey, Newman, Priestley and former heavyweight champion George Foreman are all listed as co-owners of IndyCar teams, and the allure is as varied as their day jobs.
Newman competed for years in the Can Am Series, while Priestley started driving in 1991 and made it to the Indy Racing League's developmental series before a serious accident in August 2002 ended his aspirations of running the more powerful cars.
Others grew up around the sport. Aikman's father, a welder by trade, moonlighted as a part-time driver. So after earning millions in the NFL, Aikman, now a broadcaster on Fox's NFL telecasts, found it more economical to own a race team than spend hundreds of millions to buy a franchise in one America's other professional leagues.
"I always thought it was a pretty exciting sport that was growing," he said. "It was strictly a business thing because the last thing I needed was something that required more of my time. Others probably got involved for the same reason."
For years, the sport's popularity revolved around famous drivers like Andretti, Earnhardt, Foyt and Petty, whose children and grandchildren kept the family legacies alive.
Now the big names are coming from a wider spectrum.
Foreman and Stanford football coach Jim Harbaugh are co-owners with Panther Racing. Dempsey, better known as Dr. McDreamy on ABC's hit series "Grey's Anatomy," owns part of Tony George's Vision Racing team.
Letterman, the award-winning late-night talk show host, has been working with former Indy winner Bobby Rahal for years, while Newman and Carl Haas formed their first IndyCar team in 1982 and began competing in 1983.
Those who have been around racing for decades, such as Roger Penske, believe it's a good thing for the sport.
"If they're really hard-core fans, I think it's great," said Penske, whose 14 Indy 500 wins are a record. "It's good to get them in, and they certainly can be an asset when looking for sponsors. I think it's a huge benefit. It's almost like having Tiger Woods as a partner if you're building a golf course."
But fame away from the track hasn't always translated to success on it.
Priestley's team, which is co-owned by Jim Freudenberg and former IRL driver Sam Schmidt, failed to qualify for last weekend's Indy 500 and is now re-evaluating its future. Aikman's team, Hall of Fame Racing, which he co-owns with two Arizona Diamondbacks executives, has yet to post a top-20 finish this season with driver J.J. Yeley.
There are exceptions.
Rahal, the 1986 Indy winner, and Letterman owned Buddy Rice's Indy-winning car in 2004. Panther Racing catapulted Sam Hornish Jr.'s career with back-to-back series titles in 2001 and 2002, and now employs Vitor Meira, who was runner-up to Scott Dixon in Sunday's race.
Gibbs has won three Cup titles -- Bobby Labonte in 2000, and Tony Stewart in 2002 and 2005 -- and has this year's points leader, Kyle Busch, in his three-car lineup.
And over the past 25 years, Newman's team has won 105 IndyCar races, 106 poles and eight points titles, including the last three in Champ Car. The team has also had some of the world's best-known drivers -- Mario and Michael Andretti, Nigel Mansell, Paul Tracy and Sebastien Bourdais -- under its banner.
After the split between the IRL and CART, Newman stayed away from Indy until this month. Fans embraced his return.
"We've won eight championships and come in second twice at Indianapolis but never won the 500," Newman said on the first day of qualifying. "It's wonderful to be running against Roger, Rahal, Michael and all those guys. It's comfortable."
The celebs have also added their cast of friends to race week festivities.
Two-time Indy winner and "Dancing With the Stars" champion Helio Castroneves spent race week hosting a group of former competitors from the television show including Wayne Newton and Castroneves' partner, Julianne Hough. Priestley invited former co-star, Luke Perry, and had Colts tight end Dallas Clark lined up to work on the team's pit crew.
Indiana men's basketball coach Tom Crean, whose wife, Joani, is the sister of Jim and John Harbaugh, the Baltimore Ravens coach, watched the race from the Panther Racing suite. NBA star Baron Davis, NFL Hall of Famer Marcus Allen and Olympic skier Bode Miller were all race-day guests of Jay Penske's Luczo Dragon team. Penske is the son of Roger Penske.
"I know a couple of players who have gotten involved, like Carmelo Anthony," Davis said. "I think there's just an appreciation among athletes for the speed, precision and great teamwork it takes in auto racing."
But the one common theme that keeps celebrities involved in racing is their zeal for the sport -- not the red carpet introductions.
"I think celebrities like racing for different things. George (Foreman) has a huge car collection, the biggest I've ever seen, so I think that he was bitten by the motorsports bug," Panther co-owner John Barnes said. "That's what drives them and brings them into sports of all forms.
"I think the sport has tremendous openness, too, especially IndyCar racing. Jim (Harbaugh) used to say that if he made it to the Super Bowl, his dad couldn't come in the locker room before the game. In IndyCars, you have breakfast with the drivers on race day, and I think that's part of the attraction, too."