McLaren team boss Zak Brown believes there are at least two IndyCar drivers capable of racing in Formula One at the moment.
In an interview with ESPN last year, reigning IndyCar champion Josef Newgarden expressed an interest in driving in F1, opening the discussion over why top-level IndyCar drivers are rarely in the running for seats in Formula One.
When the issue was raised with Haas' Guenther Steiner -- team principal of the only American F1 team on the grid -- he said he would be apprehensive about dropping an IndyCar driver straight into F1. But speaking at this weekend's Daytona 24 Hour race in Florida, Brown said he would consider both Newgarden and four-time IndyCar champion Scott Dixon if the opportunity arose.
"I disagree with Guenther Steiner's comments that none of the IndyCar drivers would be capable in a Formula One car," he said. "There's a few I'd put in.
"Specifically I think Josef Newgarden is an outstanding talent and I think Scott Dixon is an outstanding talent.
"I don't subscribe with the view that drivers can get too old, I think what happens is that drivers ultimately lose motivation and that's what catches up with them. If you look at someone like Michael Schumacher, he was very competitive into his forties and had he not taken those few years off, those last couple of tenths he was off I don't think he would have been -- and he was in his forties.
"Fernando [Alonso] has that same type of dedication -- I think Fernando is driving as well as he has ever driven and just because he's going to turn 37 later this year I don't think the stopwatch is going to get any slower. On the flip side, you got someone like Nico Rosberg who said, for whatever reason, I'm done.
"So someone like Scott Dixon [at 37 years of age] reminds me of Fernando, where he is extremely fit, very dedicated and as fast as ever, and I think Scott Dixon would be very competitive in a Formula One car today."
But Brown says F1's strict testing regulations means opportunities to make the switch from one series to the other are limited.
"The biggest challenge you have is the lack of testing. Until those rules change we only get eight pre-season days of testing, and even that is with one car and you rotate drivers. So to take away a day from Fernando's four [days of pre-season testing] or Stoffel [Vandoorne]'s four makes no sense.
"Until that rule changes it will be difficult for a driver outside of the F1 arena or Formula 2 to break into F1 because you have such a disadvantage in the system and it doesn't really allow you to bring someone in. I think it's great that Toro Rosso brought in someone like Brendon Hartley [World Endurance Championship champion], because there's risk with that decision, but he knows all of those tracks as well."
Reporting by Bob Pockrass