Mercedes is at the centre of a controversy that has been simmering away throughout the off-season and into pre-season testing.

The German carmaker is thought to have found a loophole in the new regulations that ensures its engines legally meet the 16:1 compression ratio at ambient temperature, while hitting a number closer to 18:1 at operating temperature.

The allowed compression ratio was dropped from 18:1 to 16:1 as part of the sweeping new hybrid regulations introduced for this season.

With other manufacturers up in arms over the potential loophole, the FIA has opted to conduct a vote over whether change to the regulations should be enacted mid-season.

The change would see the compression ratio measured at both ambient and operating conditions, with the vote to take place next week.

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“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,” an FIA statement read.

“Following validation of this approach, a proposal has been submitted whereby, from 1 August 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.”

According to The Race, a successful vote would include at least four of the five manufacturers being in favour, as well as the FIA and Formula One Management.

Ferrari, Audi, Honda and Red Bull/Ford are all likely to vote in favour of the change which would give the FIA and FOM the deciding votes.