The idea of bringing back V10 engines to Formula 1 is beginning to win over supporters in the paddock, with sources suggesting that Ferrari is ready to back the idea.
However, even with key figures throwing their weight behind a reintroduction there are still major hurdles to overcome, and opponents who need convincing it is right for F1's future, before it can become a reality.
The situation has emerged at a time when F1 chiefs are already contemplating future engine regulations for the rules cycle that will follow the next generation of turbo hybrids that are currently set to run from 2026-30.
One proposal being considered, if the switch to fully sustainable fuels from next year is deemed a success, is to ditch hybrid engines and revert to either normally aspirated or turbo V10 powerunits after that.
This is something that FIA president Mohammed Ben Sulayem mentioned recently in a social media post talking about the future direction of F1.
"We should consider a range of directions including the roaring sound of the V10 running on sustainable fuel," he said.
"Whichever direction is chosen; we must support the teams and manufacturers in ensuring cost control on R&D expenditure."
Working group discussions
The FIA has set up a working group to speak to relevant parties - which are believed to include F1 engine manufacturers, teams and fuel suppliers - about future engine ideas including the V10.
Discussions are ongoing and the feedback from some parties is understood to show support for the V10 proposal.
But talks with and between relevant stakeholders have also thrown up some more interesting responses, with one radical proposal first revealed by Auto Motor und Sport of not only going to V10s but doing it earlier than 2031.
An idea has been floated of ditching the new 2026 engines completely, sticking with the current powerunits until 2028, and then going down the V10 route from 2029.
However, such a bold U-turn on next year's new rules would almost certainly not gather the backing needed, as it would require unanimous support from teams.
And that unanimity does not appear to be forthcoming, especially because of the impossibility of what Audi would do for an engine, and where some teams like Red Bull would be left.
But another idea has also surfaced. It is to go ahead with the new turbo hybrids for 2026 but begin preparations for a switch to V10s perhaps as early as 2029.
Nothing has been formally proposed to teams yet, and ideas are simply being floated right now for a bit of blue-sky thinking.
But the fact that discussions are being framed in this way indicates that the notion of a V10 return is no longer pure fantasy.
Divided opinions
Right now, three manufacturers are wholly against anything other than pushing on with the plans for 2026-30 that they have spent hundreds of millions of dollars developing.
Audi does not have a current turbo hybrid to use, so it would be unable to join the grid as planned next year if the engine regulations F1 has right now were carried forward.
Mercedes and Honda are understood to not want a change after all the effort they have made.
From Mercedes' perspective, while it is not against an earlier reintroduction of V10s in principle, there is no way it can change plans for next year. So a V10 move could only come in 2029 or 2030 at the earliest.
Development of Mercedes' 2026 powerunit is in full swing and there is no ability to deliver current-spec engines for next season as manufacturing has been switched off for beyond this year - which means no supply is possible for itself nor its customers.
It is also understood that, while Mercedes is not against an earlier reintroduction of V10s, it believes it would not be able to supply customer teams were the current engine ruleset to be extended.
But others, while in no doubt that the 2026 rules have to go ahead, are not totally against the prospect of taking a different path over the following few years.
Red Bull team principal Christian Horner said in China that, amid questions over whether the new rules will work, the prospect of a V10 had its attractions.
However, he reckoned that despite "limitations" of the 2026 regulations, it was probably too late to consider anything other than committing to the new turbo hybrids for now.
"We've ended up in a situation where the chassis is having to compensate a huge amount for perhaps some of the shortcomings of the split in electrification and combustion," he said, when asked by The Race about the possibility of a return to V10 engines.
"But it's sort of 10 past midnight and Cinderella's left the building. The romantic in you [says] a V10, a screaming V10, so long as it's done responsibly with fully sustainable fuels, is hugely attractive.
"But I think the big question is: when would that be for? And what will be the game plan between where we sit today and then?"
Red Bull may not be the only manufacturer in favour of the V10 move, with sources claiming that Ferrari's senior road car management sees potential in it.
Ferrari has not officially confirmed its stance and has so far steered clear of any public confirmation of its position regarding a change of tact over the future engine regulations.
Asked during pre-season testing about the idea, team principal Fred Vasseur dodged a firm answer by simply stating it was too early to start thinking about the shape of long-term rules.
"It looks to be very early for me to discuss about the engine of 2031, or whatever," he said.
"We haven't even started with the next homologation. We still have some huge topics on the table, and we didn't even start this journey. So, let's be focused on this before moving on to discuss about 2030 or 2031."
However, it was interesting to hear Lewis Hamilton, who is close to Ferrari chairman John Elkann, be so openly in favour of the V10 route when asked about it at the Chinese Grand Prix.
"It's no secret the V6 has never sounded great," he said.
"I remember the first time I came to a Formula 1 race in 1996 in Spa, I remember arriving and Michael [Schumacher] coming through Turn 1 and my rib cage just vibrating. I was so hooked, like it was the most amazing thing that I felt and heard before.
"Over the years, we've lost that. So if we're able to move back to those amazing sounding engines, and we're still able to meet the sustainable goals, why not?"
'The train has left'
Should Ferrari support the V10 plan then it would certainly add some political momentum to the idea, and probably even trigger a more serious evaluation of a switch earlier than 2031.
However, McLaren team boss Zak Brown - whose team will remain a Mercedes customer from 2026 - said it was probably too late to undo what is already planned for the next generation of turbo hybrids.
"I think a V10 definitely, as Christian said, would be pretty cool with sustainable fuels," he said.
"But I don't really see how you can unwind what's in place, really because of all the different powerunit changes that are happening right now: Audi's coming in, Alpine's going to Merc, Ford's joining. Logistically, I'm not sure how you put the genie back in the bottle."
Alpine boss Oliver Oakes, whose team has just committed to shutting down its own Renault engine programme in favour of taking customer Mercedes engines from 2026, agreed that it was now too late to consider the 2028 plan for V10s.
"I think it's quite a romantic idea but obviously the train has left the station now for 2026," he said.
"I think it is something probably beyond that that'll be looked at, because it does sound quite good for Formula 1 to go back that way a little bit."
There is no consensus nor clear road map just yet but, based on the shifting of messaging in the paddock, a return to V10s seems no longer to be a question of 'if' any more. It is now more about when.
