Formula 1 engine manufacturers are split over what direction to take with the new power unit set for 2025 or 2026.

So far, it has been confirmed the aim is to make the next generation of engines cheaper and more efficient with greater electrification and 100% sustainable fuels.

However, according to Auto Motor und Sport, the disagreement is over the engine formula with Red Bull, who will launch their new Powertrains division next year, and Ferrari arguing for a return to noisier engines with four cylinders.

"I think that the combustion engine does have a future, so why not introduce high revving engines that sound fantastic, and that are doing it in an environmentally friendly manner?" Horner said earlier this summer.

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"I think that biofuel and sustainable fuels enable you to do that.

"Electrification, I know, politically it's being pushed, but actually is it the right route for 25 and 30 years' time?

"I think F1 could play a key role with the fuels and with the fuel partners that we have on sustainability and zero emissions, with a high-performance, high revving emotive engine.

"Wouldn't it be fantastic if we went that route? I'm sure every Grand Prix would be packed."

However, perhaps unsurprisingly given their domination of the V6 hybrid era, Mercedes are keen for more of an evolution rather than a revolution.

"I would disagree with Christian because it's what we think, but we are not the most relevant generation anymore," said team boss Toto Wolff.

"When you ask an 18-year-old or 22-year-old, what relevance noise has, most of these guys consume it via different screens where noise has little or no relevance.

"I personally like it too, and I'd like to have a 12-cylinder that screams down the road. But, as a matter of fact, we are a sport and we are a business.

"I think we would lose complete relevance with our partners, sponsors, and major stakeholders if we weren't looking at the environment and the impact that we make.

"I think it would be totally misaligned of where the world is moving, and probably turn every single business partner away from F1 if we stick with internal combustion engines that scream, even though we may like them."

Renault was a big backer of four-cylinder engines when the current power unit regulations were being negotiated back in 2010/2011.

A decade on, however, that view has changed.

“If we have CO2-neutral fuel, we don’t need a four-cylinder engine,” executive director Marcin Budkowski was quoted by PlanetF1.

“The V6 is already there. Why reinvent the wheel? It would mean massive modifications to the car, more weight and more cost.”

Audi or Porsche, both of which are owned by VW, are also known to be interested in the new power unit regulations.

But if the manufacturers can't make their own decision by the Italian Grand Prix next month, AMuS also reports the FIA could step in to postpone the new engine until 2026, giving the governing body and F1 complete freedom to come up with their own regulations.