Ross Brawn says Formula One must decide whether it wants to continue on a steady path towards electric power or bring back the noise of high-revving internal combustion engines.

The former Mercedes team boss conducted an hour-long interview with ESPN last year, speaking about multiple aspects of the sport. Above all, Brawn said F1 needed a long-term plan and he believes one of the key areas that will determine the direction of that plan is the sport's engine formula.

F1's last major engine regulations change came in 2014, when it ditched naturally-aspirated V8 engines for a fuel-efficiency formula based around V6 turbos. In that time manufacturers within the sport have made huge strides with new technologies, achieving unprecedented levels of thermal efficiency for internal combustion engines.

Despite the impressive technology involved, the power units have not been welcomed by the majority of fans, who have failed to be won over by the muffled exhaust note of the turbocharged engines. With the road car industry shifting its focus increasingly towards electric power, Brawn says F1 must now make a decision on which direction it wants to go when the next set of engine regulations are framed for 2020.

"I think that's one of the key things that Formula One has to decide about what it wants to be for the future," he told ESPN. "Does it want to be mainstream technical innovation aligned with road transport or is it a sport that can afford to step outside of that and say we want the best solution to entertain the fans, be economically viable and be interesting.

"If we looked at it purely as a requirement to be a racing engine, not a requirement for manufacturers justifying their development because they get technical spin off from it, which combination of those routes do we take? Ultimately, with the way road transport is going, we are going to be with electric and fuel cell cars, so does Formula One follow it all the way and end up with an electric motor or a fuel cell where there's no noise? That's not appealing to me, but who knows?

"So when you look at that roadmap, do you end up with engines of that sort or do you say we have already gone far enough and end up with a racing engine with all the emotions that that creates for the fans, and just accept Formula One won't be aligned with the sorts of cars that are driving down the street in five or ten years' time, because not all of us will be driving internal combustion engines."

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Brawn believes it is important to understand what fans want from F1, rather than play to the whims of the manufacturers involved.

"The unintended consequence of the current engines was twofold: one, they were more expensive than anyone anticipated, and secondly they don't make any noise, which the fans loved. I have to make a confession that I haven't been to a race since I stopped, so I don't know what they sound like. I heard them on the dyno when I was at Mercedes but I have not heard them racing in a car.

"People tell me all about it and I don't hear many compliments for the noise of the current engines, which is a great shame as they are very, very interesting, but there does seem to be an element missing.

"How important is that element? Can you really quantify the impact that these quieter engines have and is it really detrimental to the sport or is it just a talking point? Who knows? That's the sort of thing that needs to be understood, because really the only way to go back to a noisy engine is to have a conventional internal combustion engine."

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Under Formula One's current governance, the teams have a large say in the rules and direction of the sport, with the six biggest sitting on Formula One's Strategy Group with the FIA and commercial rights holder. Asked what direction he thinks the sport should take, Brawn said the decision would ultimately come down to what the teams want.

"Well I wouldn't, what I would do is sit down with the manufacturers and sit down with the teams and start to work out what their objectives and requirements are. How do they see the future and how do they see racing engines in five years' time. What sort of engines do they want to see? Is this connection with roadcars an essential element, or do they also acknowledge that leaves you with a form of electric motors that, if it doesn't engage the fans, means Formula One is not going to be successful.

"I don't know what the solution is but this is one of the debates that has to happen to understand where Formula One is in five years' time."

Interview conducted by Jennie Gow