"You're going to have some confrontation between father and son you probably wouldn't have with a different boss, because either side know they can get away with it," Mario said. "It's something different. I'm just glad I never had to drive for my dad."
Before announcing their working relationship, Bobby discussed with Graham how they would have to treat each other "on a higher plane" than just father and son.
"The father-son thing, that can be great, and it can be really destructive too," Bobby said. "There can be a big emotional aspect to that, and that's not good. So we have to really discipline ourselves to ensure that there isn't that emotional element in there, and that's not always easy."
With Father's Day coming up, Marco and Graham have a chance to give a gift few sons can to their dads.
"Hopefully a pole and win," Marco said. "That way I don't have to get him a card or anything."
The series runs Saturday at Milwaukee, a race Michael Andretti's marketing company is promoting and where he won five times, including a 1991 CART race when he shared the podium with his cousin, John, the runner-up, and third-place finisher Mario.
"Well, I couldn't ask for a better present that's for sure," Michael said when asked about the possibility of Marco getting to Victory Lane there on Father's Day weekend. "It'd be another special moment at Milwaukee if that were to happen. ... That would just totally add to it."