As soon as the Formula 1 teams get back to work after the New Year, the way Mercedes and Red Bull exploit a loophole in the regulations to extract more performance from their new power units will once again be high on the agenda for manufacturers who missed the boat.

Mercedes and possibly Red Bull Ford are using a trick to increase the compression ratio in a cylinder. The regulations state that it may not be higher than 16.0 to 1. But teams also know: the higher the compression ratio, the more performance an engine delivers.

It’s now known that clever designs are being used to reach a higher limit while still staying within the rules. Manufacturers achieve this because the compression ratio is measured only when the engine is not at full operating temperature at the circuit.

The engines contain components that expand once the engine is warm, pushing the piston closer to the top of the cylinder than when the engine is cold. This increases the compression ratio, yielding extra performance and lower fuel consumption.

Reportedly, this gives the Mercedes teams and the two Red Bull teams an advantage of possibly four tenths of a second per lap. Margins like that would mean Ferrari, Audi, and Honda are fighting a losing battle in advance for the 2026 season.

An ‘obstacle’ for these teams remains that the FIA sees no issue. The technical staff of the governing body have been involved from the start in the development of the engines and have already homologated them. The engines have now gone into production.

Nevertheless, Ferrari particularly continues to lobby hard to have this trick banned at some point. Through the Italian press, it is now being leaked that the Scuderia believes six or seven Grand Prix weekends should be enough to force the FIA to mandate changes after all.

However, the FIA still isn’t budging. At the moment, the engines from Mercedes and Red Bull are not considered illegal, so it’s mainly about keeping up the pressure.

This may all lead to Ferrari lodging a protest against the Mercedes teams and the Red Bull teams in Melbourne. Regardless of the outcome, it could cause significant reputational damage to the sport.