INDIANAPOLIS -- The cars in this Indy 500 have something no car ever has had in this historic event, and it could decide the outcome.
It's called "push-to-pass," a small and temporary horsepower boost that few fans completely understand.
Push-to-pass isn't new, but it's new for the Indy 500. And the drivers have differing opinions on how much impact it will have on the race.
"A lot," Tony Kanaan said.
"I don't think it will change anything," Marco Andretti said.
The steering wheel has a button on the upper right side (officially called the overtake button) that gives the engine an 18-second power boost between 5 to 20 horsepower.
Each driver can use the button up to 15 times during the race. Kanaan thinks the key is having a couple of pushes down the stretch.
"It's a long day," Kanaan said. "You're going to need to make sure you still have some [pushes] left in the last 20 laps. The restarts are where we'll use it the most. But you'd hate to lose the Indy 500 because you didn't have one left on the last restart. You have to be smart there."
Easier said than done, claims defending Indy 500 winner Helio Castroneves, who starts on the pole Sunday.
"It will be hard to save them," Castroneves said. "I'll be thinking, 'What do I need to do here?' It's such a long straightaway and it's so tempting. The button is right there. You've got to use it at the right time."
The straightaways at Indianapolis Motor Speedway are five-eighths of a mile -- the longest of any oval track in the series.
Is the overtake button an excellent chance to find a little extra power on the straights to get by another car?
"It's not," Andretti said. "When you're dealing with 650 horsepower, that 5 extra horsepower doesn't make a difference."
The amount of boost is a bit of a gray area. It depends on track conditions, weather and the speed a car is going when the driver pushes the button.
Andretti doesn't believe someone will win or lose based on the boost button.
"This race is more about whether you can keep it flat [full throttle] off the corners," Andretti said. "That's what I'm looking for. But the push-to-pass? I've never felt it, honestly. It's not exactly a kick in the butt."