F1 rules work against drivers from 'outside' switching - Zak Brown

Haas team boss Gunther Steiner recently claimed that there were no American drivers ready for F1, with one-time Indianapolis 500 winner Gil de Ferran and former F1 driver Sebastien Bourdais defending America's talent.

And while Brown says that Penske winner Newgarden is "outstanding" and New Zealand's four-time IndyCar champion Dixon (both pictured) is "exceptional", he says it would be difficult to justify the testing required to get them up to speed.

"The biggest challenge you have is the lack of testing," Brown said.

"You only get eight pre-season days of testing and even that is with one car, so you rotate drivers.

"To take away a day from Fernando [Alonso]'s four and Stoffel [Vandoorne]'s four makes no sense.

"So until that rule changes, it will be difficult for a driver outside of the Formula 1 arena, or Formula 2, to break into Formula 1, because they have such a disadvantage.

"The system doesn't really allow you to bring someone in, so I think it's great that Toro Rosso took someone like Brendon Hartley because there's risk with that decision - but he knows all those tracks.

"Specifically, I think Josef Newgarden is an outstanding talent, and Scott Dixon is an outstanding talent."

While Dixon is 37-years-old, Brown says age is not a hindrance in F1, and that it comes down to motivation.

"What happens to drivers is that they eventually lose motivation, that's what catches up with them," he said.

"So if you look at someone like Michael Schumacher, he was very competitive into his 40s.

"Had he not taken those few years off, those last couple of tenths [of a second] he was maybe off [on his return in 2010], I don't think he would have been.

"Fernando has that same type of dedication. He is driving as well as he's 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.

"Someone like Scott Dixon reminds me of Fernando, where he's extremely fit, very dedicated, as fast as ever, and I think he would be competitive in a Formula 1 car."