Mercedes rivals pushing for Australian GP rule change over F1 2026 engine loophole – report

Mercedes’ rivals are targeting a change to the engine compression ratio rules ahead of the opening race of the F1 2026 season in Australia, it has emerged.

Reports over recent months have claimed that two engine manufacturers, widely named as Mercedes and Red Bull Powertrains, have identified a loophole in the new engine regulations related to compression ratio.

Mercedes rivals pushing for rule change over F1 2026 engine loophole

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The rules for F1 2026 state that the compression ratio in a cylinder can be no higher than 16.0, a drop from the 18.0 ratio under the previous engine regulations.

With the compression ratio only measured when the engine is not running at full temperature on track, it has been suggested that the manufacturers have found away around the new rules by increasing the compression ratio to 18.0 when running hot.

If true, this could hand the manufacturers at the centre of the claims a major performance advantage in F1 2026.

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As reported by PlanetF1.com, the FIA held a meeting with “technical experts” on January 22 – four days ahead of the first pre-season test in Barcelona – after rival manufacturers reportedly aired concerns about the loophole.

Two further meetings have been held this week with the FIA once again meeting with technical experts on Monday. The Power Unit Advisory Committee (PUAC) then met on Thursday.

It has emerged that Mercedes’ rivals are pushing for a change to the way engine compression ratio is measured in time for next month’s Australian Grand Prix.

A report by The Race has claimed that Mercedes’ competitors are aiming to launch a proposal to ensure that compression ratios are measured when hot.

This could be done by either using sensors when the cars are out on track or taking measurements in the garage when engines reach operating temperature.

It is said that the three engine manufacturers most upset with the loophole being exploited – Ferrari, Honda and Audi – have potentially persuaded Red Bull to join their cause.

Recent reports have indicated that Red Bull Powertrains’ grip on the compression ratio loophole is not as firm as that of Mercedes.

As such, it could suit RBPT – which is working in collaboration with US manufacturer Ford – to join efforts to close off the loophole.

Red Bull’s outlook on the matter is of particular importance as any significant change to the power unit rules requires the backing of four of the five engine manufacturers, along with the FIA and FOM, according to the governance procedures of the PUAC.

If the four remaining engine manufacturers are aligned in opposition, Mercedes’ hopes of the rules remaining unchanged would then appear to rely on the FIA and FOM.

Speaking to PlanetF1.com and other media outlets this week, Toto Wolff, the Mercedes team boss, insisted that the team had “very positive” communication with the FIA throughout the development of its F1 2026 engine.

And he called for the manufacturers unhappy with the situation to “get your s**t together”, claiming Mercedes’ competitors are looking for already looking for excuses.

Wolff said: “I think we need to have more work done at that stage, as when it comes to the engine question, I just don’t understand that some teams concentrate more on the others and keep arguing a case that is very clear and transparent.

“Communication with the FIA was very positive all along.

“And it’s not only on compression ratio, but on other things too – and specifically in that area, it’s very clear what the regulation says, very clear what the standard procedures are on any motors, even outside of Formula 1.

“So, just get your s**t together. Doing secret meetings and sending secret letters, and keep trying to invent ways of testing that just don’t exist is [not the right way to approach things].

“I feel like I can just say at least from us here, we are trying to minimise distractions, and minimising distractions is looking more at us than everybody else when it’s pretty clear what the what the regs say, and also pretty clear what the FIA has said to us and has said to them so far.

“But maybe we’re all different. Maybe you want to find excuses before you even started why things are not good.

“Everybody needs to do it at the best of their ability, but that is really not how we how we would do things, especially not after you’ve been told a few times that is fine, it’s legal and it’s what the regulations say.

“Again, if somebody wants to entertain themselves by distraction, then everybody’s free to do this.”

In an interview with select media including PlanetF1.com last month, meanwhile, Red Bull Powertrains boss Ben Hodgkinson – who previously worked at Mercedes High Performance Powertrains – argued that the storm about an engine loophole was “a lot of noise about nothing.”

He explained: “I think there’s some nervousness from various power unit manufacturers that there might be some clever engineering going on in some teams.

“I’m not quite sure how much of it to listen to, to be honest. I’ve been doing this for a very long time and it’s almost just noise. You just have to play your own race, really.

“I know what we’re doing. I’m confident that what we’re doing is legal. Of course, we’re taking it right to the very limit of what the regulations allow.

“I’d be surprised if everyone hasn’t done that. So my honest feeling is I suspect it’s a lot of noise about nothing.

“I expect everyone’s going to be sitting at 16. That’s what I really expect.”

Additional reporting by Mat Coch and Thomas Maher

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