FIA confirm official vote over Mercedes F1 compression ratio row
The FIA have confirmed that an official vote has been launched among Formula 1’s power unit manufacturers following the geometric compression ratio controversy that has overshadowed the early stages of the 2026 season.
The issue came to light during the second round of pre-season testing at the Bahrain International Circuit, where discussions intensified over how compression ratios should be measured under the new power unit regulations. At the centre of the debate is Mercedes, who are understood to have identified an interpretation of the rules that allows their engine to comply with the mandated 16:1 geometric compression ratio when stationary, while increasing to the previously permitted 18:1 ratio once the engine is running under operating conditions.
Such a difference, while appearing minor on paper, could deliver a significant on-track advantage. It is estimated that the higher ratio under race conditions may unlock approximately 15 additional brake horsepower — a potentially decisive gain in a tightly contested championship battle.
In response, the FIA convened a meeting of the F1 Commission to address concerns raised by rival manufacturers. Following weeks of technical discussions between the governing body and engine suppliers, a new proposal has now been formally submitted to a vote.
Under the suggested amendment, compliance with the 16:1 compression ratio limit would need to be demonstrated not only at ambient temperatures — as currently stipulated — but also at a representative operating temperature of 130°C. This adjustment aims to ensure that teams cannot exploit temperature-related variances to achieve higher compression ratios once the engine reaches race conditions.
In an official statement, the FIA confirmed the process that has led to this point.
“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,” the statement read. “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.”
The timeline of the proposed change is particularly significant. Even if the vote passes, the revised measurement procedure would not come into force until August 1, 2026. That means Mercedes could, in theory, continue to run their current concept for the opening phase of the season before making any necessary adjustments ahead of the rule’s implementation.
Such a scenario could provide the Brackley-based outfit with an early competitive boost, especially across the first several races of the campaign. Given how finely balanced the field is expected to be under the sweeping 2026 regulations, even a marginal power advantage could translate into crucial championship points.
The vote itself will be decided by the five registered power unit manufacturers: Mercedes, Ferrari, Audi, Honda and Red Bull Powertrains. Each supplier has one vote, and it is understood that a four-to-one majority will be required for the proposal to pass.
The political dynamics surrounding the decision add further intrigue. Mercedes currently supply engines to four teams on the grid — their own works outfit, plus Williams, Alpine and McLaren. Any ruling that forces a mid-season redesign would therefore have implications not just for Mercedes, but for a substantial portion of the field.
Conversely, rival manufacturers must weigh the competitive fairness of the situation against the potential disruption of introducing a regulation change mid-season. While the FIA’s proposal has been framed as a clarification rather than a fundamental rewrite of the rules, the impact could still be considerable.
At this stage, it remains unclear how each manufacturer intends to vote. Some may argue that the spirit of the regulation was always to cap compression at 16:1 under true operating conditions, while others could contend that Mercedes have simply maximised what the current wording allows.
The final decision is expected within the next 10 days, after which the FIA will confirm the outcome. As always, any amendment must also receive formal approval from the FIA World Motor Sport Council before becoming binding.
With the 2026 season poised to usher in a transformative new era for Formula 1, the compression ratio debate underlines just how finely engineered — and politically charged — the sport’s technical regulations can be.
