FIA announce official F1 vote over Mercedes compression ratio controversy

An update has been announced regarding the geometric compression ratio controversy that has hit the start of the 2026 F1 season, following a meeting of the F1 commission.

During the second round of Bahrain pre-season testing this week, the commission met to discuss how geometric compression ratios would be measured within power units, after Mercedes found a clever quirk which allowed the compression ratio to be at the allowed 16:1 when the engine is stationary, but then increase to the previously allowed 18:1 when moving, something that could allow roughly an extra 15 brake horsepower.

And now, the FIA have revealed a proposal has been put forward that would mean the ratios are measured both at high temperatures and ambient temperatures, and that power unit manufacturers are due to vote on whether to introduce that rule or not. An outcome is expected to be announced 'within the next 10 days'.

If the vote passes, the new rules will only actually come in on August 1, meaning Mercedes would have almost six months to change their power unit, and could give themselves an early boost in the first few races of the season before switching up their power unit concept.

In an official statement following the meeting, the FIA said: "Over recent weeks and months, the FIA and the power unit manufacturers have collaboratively developed a methodology to quantify how the compression ratio changes from ambient to operating conditions. Following validation of this approach, a proposal has been submitted whereby, from August 1 2026, compliance with the compression ratio limit must be demonstrated not only at ambient conditions, but also at a representative operating temperature of 130°C.

"The vote has been submitted to the power unit manufacturers, and its outcome is expected within the next 10 days and will be communicated in due course. As with all Formula 1 regulatory changes, any amendment remains subject to final approval by the FIA World Motor Sport Council."

How many votes will be required to implement the new rules?

Following several meetings of the power unit advisory committee [PUAC] recently, an e-vote has been submitted by the FIA to the power unit manufacturers, and they will have 10 days to decide which way to vote.

Mercedes supply four teams on the F1 grid in Williams, Alpine, McLaren and the works Mercedes team, so any ruling could be huge for all of those teams.

The five power unit manufacturers that get a vote on the matter are Mercedes themselves, Ferrari, Audi, Honda and Red Bull powertrains, who are a power unit supplier for the first time this year.

It is believed that any vote needs at least a 4-1 majority to be passed through, and it remains unclear at this stage which way the power unit providers will vote.

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