Formula 1’s first proper governance scrap of the 2026 rules era is about as on-brand as it gets: a single line in the technical regulations, a late tweak to the wording, and a paddock suddenly split between “clever engineering” and “that’s not what we meant”.
On Wednesday in Bahrain, the FIA confirmed it has triggered an e-vote among the Power Unit Advisory Committee (PUAC) on a new way of measuring the 2026 power unit compression ratio — a move that could close off a grey area some manufacturers believe has been exploited over the winter. The vote is expected to conclude within 10 days and, if passed, the amendment would then need final sign-off from the FIA World Motor Sport Council.
The regulation at the heart of the dispute is Article C.5.4.3, which sets the maximum geometric compression ratio at 16.0. That limit has sat there unchanged through 14 iterations of the 2026 technical regulations since the first publication in 2022.
The controversy was sparked by an addendum made in October 2025, specifying that the measurement procedure would be carried out at ambient temperature — effectively when the car is parked and the power unit has cooled to the surrounding environment. That’s a small clarification on paper, but in F1 “how you measure” is often “what you’re allowed to do”.
The argument — and it has become an argument rather than idle theorising — is whether an engine can be built to satisfy the 16.0 cap when checked cold, yet operate at a higher effective compression ratio in running conditions on track. Depending on who you believe, the performance gain ranges from “hardly worth the meeting” to “worth chasing”, with figures thrown around in the weeks since suggesting anything from negligible to 20-30 horsepower.
And this is where the politics turns sharp.
The paddock assumption has been that Mercedes High Performance Powertrains has found a way to make that operating-condition shift work, with early whispers also pointing at Red Bull Powertrains. The RBPT link has always been combustible because the company’s growth since 2022 has included a significant talent lift from Mercedes’ engine group — including technical director Ben Hodgkinson, formerly of HPP — and with it the kind of rulebook mindset that treats every sentence like an invitation.
From there, the story has acquired its most typical F1 subplot: who knew what, and when. The suggestion in the background has been that whatever Mercedes is doing became common knowledge via RBPT, perhaps because it couldn’t replicate the effect to the same extent. Whatever the truth of that, the standoff that began as three manufacturers versus two has, according to those close to the discussions, shifted into what looks like four versus one.
Timing has escalated everything. Engine homologation for 2026 arrives on March 1, when the five power unit manufacturers must submit their designs for FIA sign-off and lock-in. You can argue about intent all you like; once hardware is homologated, the scope to react gets painfully narrow.
Against that backdrop, the four non-Mercedes manufacturers pushed for a revised measurement methodology — not at ambient temperature, but at operating conditions — through PUAC discussions involving the manufacturers, the FIA and Formula One Management. Teams themselves do not sit at that table.
The FIA has now confirmed the shape of the proposed fix. The e-vote is “primarily centred on a proposed change to the assessment of the power unit compression ratio in running condition” and would, from 1 August 2026, require compliance to be demonstrated not only at ambient temperature, but also at a “representative operating temperature of 130°C”.
In other words: if you’re clever enough to pass cold and then morph into something more potent when hot, you may have to prove you still sit within the limit when the engine is actually doing its job.
Toto Wolff has been consistent in Mercedes’ public stance: the engine is legal, and the team has kept the FIA “very close” to its decisions. “That’s what we did, and we have had all the assurances that what we did was according to the rule,” he said last week.
There’s an extra wrinkle, too. Sources indicate the Mercedes power unit has already been tested at higher temperatures during an FIA visit to Brixworth and is said to have passed — which, if accurate, would take much of the oxygen out of the idea that Mercedes is running an obviously non-compliant trick. It also raises the possibility that the field is arguing over a loophole that doesn’t actually move the competitive needle because everyone is, in practice, inside the same box already.
Still, the governance mechanics matter almost as much as the engineering. PUAC votes require a super-majority: the four manufacturers pushing for change would need FIA and FOM aligned with them, leaving Mercedes unable to block it if isolated. The e-vote window expires on February 28 — one day before homologation. That’s not accidental. If you’re trying to remove a potential advantage, you want everyone to design to the same assumption before designs are frozen.
But the proposal isn’t immediate. Even if it passes, it would only come into effect on August 1 — after the Hungarian Grand Prix — which introduces a familiar F1 tension: are you creating clarity, or are you moving the goalposts mid-season? Technical directives and measurement tweaks have been used in-season before, and the sport will point to precedent. The difference here is that the sport is doing it to a power unit parameter at the dawn of a new engine cycle, with homologation just around the corner.
If the vote fails, the current wording stands, and the political temperature rises another notch. Protests against Mercedes-powered cars in the early races can’t be ruled out if rivals remain convinced there’s something worth challenging.
The larger worry being voiced in the paddock is the one that always surfaces when a clever interpretation gets targeted: whether F1 is about out-thinking the rulebook, or about protecting everyone from being out-thought. James Vowles has spoken about the need to preserve meritocracy and not punish “the best solutions”. Steve Nielsen, too, has raised the uncomfortable precedent of competitors effectively organising to close down an avenue others spotted first.
That’s the tightrope the FIA is walking now. Clarity is good; ambiguity is expensive. But so is the perception that if you’re first to the answer, the sport’s response is to change the question.
Within 10 days, we’ll know which way PUAC leans — and, more importantly, whether the first big engine-era argument of 2026 ends with a technical clarification, or the start of a longer fight dressed up as one.
