Formula 1's leading teams and engine manufacturers have voiced their concerns over proposed changes to the sport's power unit regulations set to be introduced in 2021.
Mercedes boss Toto Wolff and Red Bull team principal Christian Horner have questioned Liberty Media's new engine regulations, stating none of the sport's current engine manufacturers are keen on a change.
Renault is also understood to be in favour of maintaining the current regulation set.
Introduced for the start of the 2014 season, F1 currently operates with 1.6-litre turbocharged hybrid engine which features both heat (MGU-H) and kinetic (MGU-K) energy recovery systems.
However, the complicated power units have come under fire for their extreme complexity and cost.
A new set of regulations has been drafted ahead of a 2021 introduction in an attempt to simplify the engines, which includes removing part of the hybrid system, in an effort to bring down costs.
It was also hoped the new regulations would tempt new power unit manufacturers into the sport, though at this stage none appear interested, despite Porsche and Aston Martin having been keen observers throughout discussions.
Honda is believed to have advocated the retention of the MGU-H, a component that was set to be axed from the new engines.
“I think ultimately the governing body and the commercial rights holder have got to do what they believe is right for the sport,” Horner explained.
“It doesn't look like there's anybody new coming in, so really I think it's down to the FIA and Liberty to decide, what do they want?”
Wolff shared Horner's sentiments, adding that the lack of a new manufacturer would mean the change would expose the four current power unit suppliers to additional development costs for seemingly no gain.
“It's still very much out for discussion,” Wolff said of the current situation.
“We had a presentation that would have meant a redesign of the engine.
“All four currently in F1 engaged OEMs would have given their preference, with an understanding from our side that we maybe need a bit more noise, and a discussion around fuel consumption, that's important.
“But just for the benefit of redesigning an engine without anybody else entering doesn't make a lot of sense.
“So, if somebody would commit to come into F1 in the way that we have committed ourselves, all four of us have committed ourselves, go through the lows and highs, the expenses and investment that it needs, then let's discuss engine regulations, but if nobody's inside, it's an academic discussion.”
Though unwilling to fundamentally change their engines, the sport's current engine manufacturers are willing to cede some ground that would make the current engines louder, more powerful and include the introduction of some standard components.