F1 introduced hybrid power units at the start of the 2014 season, amid suggestions that some engine manufacturers like Mercedes would not have continued in the sport if its technology had not been aligned with that of road cars.

The sport is committed to the current engine formula until 2020, but Brawn reckons what the next generation of power units will be needs to be decided by the end of 2017.

And the Briton says F1 will need to decide whether it wants to continue to be road relevant - which could potentially mean becoming electric - or take a different direction.

"F1 has to take a hard look at what it wants from an engine," Brawn said in an interview with the FIA's AUTO magazine.

"What we've done in the last few years is align ourselves with road cars. We've got this revolution going on, and the road cars we'll have in five to 10 years' time are going to be very different.

"Can we maintain the technological marvel of F1 but acknowledge that perhaps now is the time to start diverging from where road cars are going? If we don't, logic says we should have electric or fuel-cell F1 cars in a few years' time.

"We have Formula E and that's establishing its place, but for me F1 isn't just a technological demonstration, it's a whole circus, and what's the best way of maintaining that?

"It might be time to say, 'We've had this technological marvel, but we're going to step back and think about what F1 ideally wants from an engine, which may have to contain some technologies that are relevant.'"

He added: "We have to sit down with the manufacturers, teams and interested parties and decide what we want beyond 2020. Maybe it's what we've got now but refined in terms of cost and complexity, because the engine is too expensive.

"In some ways the current engine is a technological marvel and it did re-engage the manufacturers, but if F1 starts to look at 2020 now there's time to do it without anyone feeling any competitive disadvantage, with the investments and plans being made correctly.

"You need two years to sort an engine out. By the end of next year, Formula 1 needs to know what sort of engine it needs for the future "

Mercedes will be strong

Despite the changes to the regulations, Brawn is expecting the Mercedes team to be very strong again next year, as he feels this year's advantage has allowed the German squad to switch resources to 2017 before its rivals.

"Mercedes will have been pulling resource off this year's programme onto next year very early, once they saw where they were with the car," said Brawn.

"If I was there, and I'm sure they've carried on a similar philosophy, I'd be saying, 'Right, we've got a strong car, we can only beat ourselves, let's get everyone onto next year's programme'.

"I don't know how many other teams could do that. Success breeds success. Mercedes will be strong next year, despite the greater emphasis on chassis."