When the green flag falls on the 100th running of the Indianapolis 500 on Sunday, Roger Penske marks his team’s 50th year in racing.

“The Captain,” as the 79-year-old Birmingham resident is affectionately known, will celebrate the milestones where he always does: on the pit wall. Headset on. Helping manage race strategy for his four drivers — three-time winner Helio Castroneves, Will Power, defending champion Juan Pablo Montoya and Simon Pagenaud.

“I’m not a guy who sits in the suite having a cold beer,” said Penske, who calls the race for Castroneves (Team Penske president Tim Cindric calls the race for Power, Jon Bouslog for Montoya and Kyle Moyer for Pagenaud). “I want to be on the ground.”

Said Pagenaud, IndyCar points leader: “Roger knows everything about everything in the race team. It’s incredible knowing how busy he is. He’s got more passion than anyone I know.”

It’s fitting America’s most iconic track shares an anniversary with its most revered sportsman. A legend who has won at every level of motor sports, Penske also has built the second-largest auto dealer network in the world.

Ironically, the billionaire businessman — a successful amateur racer in his 20s — might have been an Indy driver had his business ambitions not intervened

“I had a chance to go to Indy and take a rookie test in the early ’60s, but I was working for Alcoa and couldn’t get the time off,” he said. “Mario Andretti took my place. Then in ’65 I became a Chevy dealer in Philadelphia and one of the prerequisites was that I (couldn’t) be a race driver.”

The rest is history.

Penske entered his first, Sunoco-sponsored, car at the Brickyard in 1969, with his first win coming three years later.

“The decision to become a dealer ... has really turned out to be the foundation of our company,” he says. “The racing has been a common piece through all our businesses, and has helped build our brand.”

When America’s Super Bowl of motor sports celebrates its anniversary, Penske will be at the helm. He will pace the 33-car field to the green flag in a 2017 Chevrolet Camaro SS — then scramble to the pit wall and try to help Castroneves navigate the grueling 500 miles to a record fourth victory — and give Penske, the winningest owner in Indianapolis 500 history, his 17th.

Adding the Camaro to his collection — Penske paraded all 16 honorary pace cars he’s won at the Woodward Dream Cruise last August — would be “pretty special,” he said. He will stake his claim with arguably the most talented group of drivers he has assembled.

“Juan Montoya is tougher than nails,” Penske said. “Will Power is a series champion. Castroneves with three wins going for his fourth — and now Pagenaud leading the series and has the hottest hand of anybody.”

His best Indianapolis 500 memory? True to his savvy business demeanor, Penske cites a teachable moment — not a triumph.

“In 1994 we took the pole and led every lap but two and won,” he said. “Then we came back in ’95 (and) didn’t make the race. That made us a much better organization. That taught us the lesson: It’s not what you did yesterday, it’s what you do today.”

It’s a lesson he carries with him.

After Jordan Spieth’s final round collapse at this year’s Masters, Penske — who befriended the 22-year-old golf phenom — sent him a letter.

“I wanted to tell him about the problem I had in a similar situation — Indy is the Masters of our sport — and we came back stronger than ever,” he said. “Those experiences in your life that are so public really makes you a better competitor and a better person.”

In a half-century at Indy, Penske has witnessed transformational changes.

“We were running lap times of 150 mph in the ’60s,” he said. “Qualifying was over 230 mph this year. The aerodynamics have changed, which give us downforce so that (cars are) like airplanes upside down. That gives us speeds of 225 through the corners.”

Yet, paradoxically, that speed has come with safety improvements that have made a race once synonymous with fiery crashes a model of safety.

“Soft walls, Hans devices, Nomex suits ... the sport has become a technical exercise,” Penske said approvingly.

Though a native of Cleveland with business interests worldwide, Penske has adopted Detroit as his home. A week after the Indianapolis 500, he will be back in the Motor City preparing for a race perhaps even closer to his heart: the Belle Isle Grand Prix.

“In 2007 when we decided we wanted racing back in Detroit, we took on the role as promotor for the city,” he said. “Detroit is the heart of the auto industry in the U.S. and coming here right after Indy ... we get two days of national TV, which showcases our city. It’s our ability to give something back.”

This weekend, however, it’s all about the 100th.

And the 50th.

Everyone in the Penske pit knows what it means to their “Captain.”

“It’s not something we talk about all the time because it would freeze you,” Pagenaud said. “Indy is special, but anytime you win for him it’s special.”

Said Penske: “If you can run at Indy — the greatest race in the world — it can change your life and your business.”

Getting to know ... Roger Penske

Position: Chairman of the board and chief executive officer, Penske Automotive Group.

Birth date: Feb. 20, 1937 (Shaker Heights, Ohio)

College: Lehigh (BA, 1959)

Family: Wife Kathryn; five children

Career: Alcoa Aluminum (sales engineer), 1959-63; George McKean Chevrolet (general manager, owner), 1963-65; owner of several car dealerships, a truck-leasing operation, and two racing-tire distributors, 1965-69; Penske Corp. (chairman and CEO), 1969-present; United Auto Group (chairman and CEO), 1999-present

Awards: SCCA driver of the year (Sports Illustrated, 1961), driver of the year (New York Times, 1962)

Teams: NASCAR — Brad Keselowski and Joey Logano. IndyCar — Helio Castroneves, Juan Pablo Montoya, Simon Pagenaud and Will Power

Series titles: NASCAR — One (Brad Keselowski, 2012). IndyCar — Two (Sam Hornish Jr., 2006; Will Power, 2014). CART — Nine (Rick Mears, 1979, 1981, 1982; Al Unser Jr., 1983, 1985, 1994; Danny Sullivan, 1988; Gil de Ferran, 2000, 2001)

Indianapolis 500

Track: Indianapolis Motor Speedway (oval, 2.5 miles).

Schedule: Today, Carb Day (NBCSN, 11 a.m.); Sunday, race, noon, ABC

Distance: 500 miles (200 laps)

Pole: James Hincliffe

Defending champion: Juan Pablo Montoya