With one race still to go until the 2026 season actually begins, the paddock’s already deep into the kind of argument that only Formula 1 can turn into a full-blown political project: how, exactly, you’re allowed to measure something as fundamental as an engine’s compression ratio.
Rival manufacturers are pushing the FIA to tweak the enforcement of the new compression ratio limit ahead of next month’s Australian Grand Prix, after concerns that the current wording leaves room for teams to run effectively higher ratios once the power unit is up to temperature.
Under the 2026 rules, the compression ratio in a cylinder must not exceed 16.0 — down from 18.0 in the previous era. The controversy is centred on the way that figure is checked. The claim circulating in recent months is that the ratio is only measured when the engine isn’t at full operating temperature, opening the door for an interpretation (or an engineering trick, depending on your allegiance) that sees a unit comply when “cold” but behave very differently when it’s properly hot and running in anger.
The two names that have been repeatedly attached to that allegation are Mercedes and Red Bull Powertrains. Whether that’s because they’ve genuinely found something clever, or simply because they’re the easiest targets when the sport resets its rulebook, is the part nobody will say out loud. But the key point is the same either way: in a fresh regulation cycle, a perceived advantage at the power unit level isn’t just performance — it’s leverage.
The FIA has been forced to treat it as more than background noise. A meeting with “technical experts” took place on January 22, four days before the first pre-season test in Barcelona, after rival manufacturers raised concerns. Two further sessions followed this week, including another technical gathering on Monday and then Thursday’s Power Unit Advisory Committee (PUAC) meeting — the forum where the manufacturers, FIA and FOM get into the weeds of governance, clarifications and potential rule changes.
What rivals want now is not a sweeping rewrite of the regulations, but a change to the test itself: make sure compression ratio is measured when the engine is hot. The idea is straightforward. Do it via sensors while the cars are running on track, or take measurements in the garage once the power unit has reached operating temperature. Either way, the intention is to prevent a situation where compliance depends on the state of the engine at the moment the FIA checks it, rather than how it behaves across a lap in Melbourne.
According to the reporting around the talks, Ferrari, Honda and Audi are the manufacturers most agitated — and there’s a suggestion they may have even pulled Red Bull into their orbit. That’s significant, because PUAC politics are built around thresholds: any meaningful change to the power unit rules requires the backing of four of the five manufacturers, plus the FIA and FOM.
If Mercedes ends up isolated against the other four, the pathway to keeping the status quo becomes less about the engineering argument and more about whether the FIA and FOM are prepared to resist a united front from the rest of the supply base. And that’s where this stops being a technical debate and becomes a question of how the sport wants to govern the early part of a new era: do you lock things down immediately for the sake of “fairness”, or do you accept that the cleverest interpretation of the rules is part of the game?
It’s also why Red Bull’s position matters so much. Reports have suggested Red Bull Powertrains doesn’t feel as comfortable with the alleged loophole as Mercedes does, which would make it logical — from a cold competitive standpoint — to close it off before it turns into a durable advantage for someone else. RBPT is developing its 2026 package in collaboration with Ford, and in a year when everyone’s trying to establish credibility as much as lap time, the optics of being on the “right” side of a regulatory clampdown may not be unwelcome either.
Mercedes, for its part, has shown little interest in entertaining the idea that anything needs “fixing”. Toto Wolff has been characteristically blunt, insisting the team’s communication with the FIA throughout development has been “very positive” and portraying rival manoeuvring as distraction tactics.
“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,” Wolff said.
“Communication with the FIA was very positive all along.
“And it’s not only on compression ratio, but on other things too… 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…”
Wolff’s frustration is doing two jobs at once. One is defensive: if Mercedes believes it has simply built a better solution within the published framework, the last thing it wants is a late clarification that, in effect, rewrites the competitive landscape after the money’s been spent. The other is offensive: publicly framing the opposition as panicking or looking for excuses makes it harder for them to sell a rule change as a principled push for consistency rather than an attempt to pull a leader back.
Red Bull Powertrains boss Ben Hodgkinson — a Mercedes HPP alumnus, which inevitably colours how every quote is read — has taken a calmer, almost dismissive line. He’s described the whole saga as “a lot of noise about nothing”, arguing the paddock’s simply doing what it always does when it can’t yet see the true competitive order.
“I think there’s some nervousness from various power unit manufacturers that there might be some clever engineering going on in some teams,” Hodgkinson said.
“I’m not quite sure how much of it to listen to… 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… I expect everyone’s going to be sitting at 16. That’s what I really expect.”
The irony is that both sides can be telling the truth. It may well be that nobody is “cheating” and everybody will end up at 16 — and that the entire fight is about preventing a scenario that may never materialise. But F1 doesn’t wait for proof when the downside is getting caught behind for an entire cycle. If you suspect a rival has found daylight in the rules, you don’t file it away for round five. You go straight to the FIA, you build a coalition, and you try to get the interpretation nailed down before the first set of points is even on the table.
Whether the FIA moves in time for Melbourne will tell us plenty about how aggressively it plans to police the grey areas of the 2026 power unit rules. And, just as importantly, it’ll tell us who’s got the numbers when the sport’s newest political season has barely begun.
