Soon after hearing that David Letterman announced May 20 as the final taping of the “Last Show,” Bob Rahal rang up his Verizon IndyCar Series team co-owner.

“I said it looks like you’ll have no problem making the (Indianapolis 500),” Rahal said. “He replied, ‘Yeah, do you need a lap counter?’ I don’t think there are many other things more important to Dave than the Indianapolis 500.”

Letterman, 68, who’s hosted a network late-night talk show for 33 years, is retiring from the daily grind but not from one of his longtime passions.

Click it: Indy 500 winner and series champion interviews

“I am hopeful that he’ll come to more races,” Rahal added.

"Yeah, well I'd like Bobby to show up at fewer races," Letterman deadpanned. "We'll see if we can work that out."

But seriously, as a Hoosier and Ball State University graduate who as a pit reporter for ABC Sports’ Indianapolis 500 tape-delayed telecast interviewed Mario Andretti after he had crashed out in the 1971 race, the Indianapolis 500 Mile Race is one he wouldn’t miss if at all possible.

“I grew up in the back yard of the Speedway pretty much in Broad Ripple. My son (Harry) has not so my responsibility now is to impose on him the excitement and the passion and the connection that it is in my hometown,” Letterman said.

He also has been serious about educating his studio and viewing audience through the years about the technology and excitement of Indy car racing. Indianapolis 500 winners and series champions have been guests on his show in addition to special appearances by Rahal Letterman Lanigan driver Graham Rahal, who most recently presented a Top Ten list.

“They’re tremendous athletes, so worldly and great guests,” Letterman said. “To a lot of people, they don’t know what these cars are or what they’re capable of, and you want to give them a sense of what it takes to control one and what the driver has underneath them. That’s where the skill and athleticism is.”  

Though Letterman claims former USAC driver Bud Tingelstad, who was a 10-time Indy 500 starter with a best finish of sixth in 1964, is his favorite driver, Graham Rahal “is solid gold, he’s Brad Pitt.”

“Dave and I sat together at the Indy 500 when I was 4 years old,” said Rahal, 26, who has been the runner-up in the past two races. “Supposedly, I had every car and driver memorized. So Dave spent a lot of the day quizzing me. When I won my first race, I received an extremely nice bottle of Dom Perignon from him, signed. I’ve never opened it. It’s one of the coolest trophies I have.”

'I'm in' came after a single phone call

The business association began in 1996, but Bob Rahal and Letterman established a personal relationship years before through a mutual friend. Jack Hanna, longtime director of the Columbus (Ohio) Zoo who has made 75 appearances on “Late Night,” was a neighbor of the Rahals in New Albany, Ohio, and Graham’s godfather.

“I met Dave after I won the 500 (in 1986),” Rahal said. “Jack mentioned that he knew me, and the next thing I knew Dave’s people were calling to have me on the show. From the beginning, he was very knowledgeable about racing. He read the industry magazines. I’m not saying he knew how to rebuild the front suspension of a race car, but he understood a lot.

“We used to race at the Meadowlands and I would go see him and I bought him dinner one time. To this day, he says I’m the only person who ever bought him dinner. It’s a running joke. We built this relationship and one day he said, ‘If you’re ever looking for a partner give me a ring.’ ’’

That opportunity presented itself in 1996 when Rahal, a three-time CART champion, and team co-owner partner Carl Hogan – who in 1992 purchased the assets of Pat Patrick Racing -- were going their separate ways.

“When that moment arose I called Dave and said ‘Well, here’s your opportunity.’ He said, ‘I’m in’ and we’ve been together 20 years. It’s been a great relationship.”

The team won the 2004 Indianapolis 500 with driver Buddy Rice, and Letterman was in the center of the celebration.

“At the ‘500,’ fans love him. They’re lined up six deep near our hospitality unit trying to catch a glimpse of him,” Rahal said. “Dave signs autographs and chats, and he’s just so funny. He's so quick-witted. Humor is natural to him."