Fritz Enzinger, Porsche Motorsport vice-president, told BBC Sport: "It would be of great interest if aspects of sustainability - for instance, the implementation of e-fuels - play a role in this.

"Should these aspects be confirmed, we will evaluate them in detail within the VW Group and discuss further steps."

E-fuels are carbon-neutral, they can power internal combustion engines without the environmental impact of traditional fossil fuels. We can find them in different forms, including bio-fuels made from bio-mass, and synthetic fuels, which are manufactures by an industrial process that captures carbon from the atmosphere.

As they are being involved in discussions around the new engine rules, according to senior F1 figures, Enzinger stated: "Porsche and Volkswagen AG are observing the constantly changing regulations in all relevant racing series around the world. This is also the case with regard to the emerging new engine and drivetrain regulation for Formula 1 from 2025."

In the case Volkswagen Group commits to entering F1, it is highly likely it would be with either Porsche or Audi brands, sources say. It is not clear whether their entry would be as a full works team, like Mercedes, or as an engine supplier to an existing team.

It is said that VW has already had exploratory talks with three of the existing teams: Red Bull, McLaren and Williams.

Because of their level of competitiveness and absence of any ties to a car manufacturer, Red Bull is said to have obvious appeal. As Honda, Red Bull’s engine partner, is pulling out of Formula 1 at the end of the 2021 season, the team has made a deal to take over the Japanese company’s power units and run then until the end of 2024 season.

There have been no comments from Red Bull on Porsche, but last month Christian Horner, team principal, said they were open to a partnership with a car manufacturer, also known as OEMs.

"If an exciting partner comes along, then of course it makes sense to look at it very seriously, whether it be an OEM or another type of partner," said Horner.

In the meantime, Jost Capito was recently appointed chief executive at Williams. Capito has had a long career as an executive in the Volkswagen Group. But Williams declined to comment on the matter of a possible deal with Porsche.

As for McLaren, “we never comment on speculation”, their spokesperson said. We can note that their team principal, Andreas Seidl, is the former head of Porsche Motorsport, but they are taking off this season on a new customer engine contract with Mercedes.

But he is not the only former VW Group executive. New F1 president, Stefano Domenicali, joined after five years of being CEO of Lamborghini, which is part of the Volkswagen Group.

Before being CEO, he was the head of the group’s future projects. He was working on a Formula 1 feasibility study when the company was hit by the diesel-gate emissions scandal, which of course curtailed the plans.

And that was the second time in the past decade that the Volkswagen Group has shied away from joining Formula 1 after doing an investigation on the idea. They were also involved in discussions over the current engines at the start of the 2010’s before declining to focus on endurance racing.

What will the new F1’s engines be like?

The engines that are due to be introduced in 2025 will center on a hybrid power; a combination of internal combustion with an electrical regenerative element. The aim here is to have a larger proportion of their total output created by electricity and energy recovery than the engines that are being currently used in F1.

The high-tech engines used since 2014 have instigated a technical revolution in terms of thermal efficiency. Compared with the 30% of a typical road-going petrol engine, F1 engines have a thermal-efficiency rating of more than 50%. But they are complex and expensive and the sport’s bosses want to ensure the new engines are more cost-effective.

Different road-car manufacturers are growing their interest in e-fuels as a solution for carbon-neutral power as there are limitations on the implementation of electric cars for all purposes. And Porsche is one of them, they are already building its own manufacturing plant for synthetic fuels in southern Chile.

Domenicali said last month: "Electrification, full electric, is not the only way for the future [of road cars].

"So the hybridisation that we want to offer in the future is the right platform on which [manufacturers] can present their product.

"Hybrid will be a diversified platform on which they can invest and promote the efficiency of their power-unit or power-train.

"Carbon neutrality is the other element at the centre of our discussion - eco-fuel, organic fuel.

"The good thing is all the OEMs and [F1] teams share this view together."