Mercedes rivals push for intervention over F1 engine loophole - but how realistic is it?

Under Formula 1's new power unit regulations, discussion about the compression ratio flared up even before a single wheel had turned with the 2026 machinery. The ratio between cylinder volume with the piston at the bottom of its stroke and at the top was 18:1 under the previous regulations, but has been reduced to 16:1 for 2026 - partly to make it more accessible for newcomers.

Competitors had caught wind that Mercedes can comply with the 16:1 compression ratio during static tests, but might achieve a higher ratio at higher temperatures while the car is running. Audi, Ferrari and Honda jointly sent a letter to the FIA to ask for clarification, but after an initial meeting of technical experts on 22 January, the federation did not immediately appear to be planning any intervention.

Subsequently, new meetings have taken place, including that of the Power Unit Advisory Committee on Thursday. According to information obtained by Motorsport, the compression ratio was once again high on the agenda and discussed with all stakeholders, although no final decision has been made.

Rival manufacturers are still exploring ways to prompt a regulatory intervention, ideally ahead of the new season. The main focus is on adjusted measurement methods for the compression ratio.

At present, only static tests are carried out at ambient temperature, but one of the ideas floating around is to conduct those tests after the engine has first been warmed up. Testing it under hot conditions would provide a more representative picture and expose any differences. Another idea is the use of sensors while driving.

Max Verstappen, Red Bull Racing

Red Bull and FIA key to supermajority?

However, all of this is easier said than done. Already based on the PUAC governance itself, a supermajority in there is required for any change in procedure. This means that four of the five manufacturers, the FIA and F1 must all agree as a first step of the process.

In that respect, Red Bull Ford Powertrains holds an important position. With the initial letter from Audi, Ferrari and Honda, it was immediately clear that three of the five power unit suppliers were pushing for a change.

Red Bull, by contrast, was also linked to the engine loophole, but that image has been nuanced a bit in recent weeks. There have been suggestions that Red Bull may have knowledge of Mercedes’ solution, but that it would not necessarily oppose an intervention. But it could push for action if its own gains are considered smaller than those of a major competitor — in this case Mercedes and its customer teams.

Beyond Red Bull’s stance, the positions of the FIA and F1 are crucial. Both organisations usually vote with a unified front when it comes to technical matters. As mentioned, the FIA initially saw no reason to intervene, but after yesterday’s meeting it’s a matter of waiting for the federation’s updated view. When asked, an FIA spokesperson said the matter was still under discussion internally and that an update might only be shared at a later stage.

Toto Wolff, Mercedes

Photo by: Lillian Suwanrumpha / AFP via Getty Images

Time ticking ahead of homologation deadline

If the measurement procedure is revised, it could have far-reaching consequences. It would not only affect the sporting picture, but it is also closely linked to the homologation date. The 2026 engines will be homologated on 1 March, leaving little to no time for any adjustments if required - especially given engine-related changes typically require a long lead time.

Toto Wolff has made his opinion crystal clear. The Mercedes boss said ahead of the team's season launch that other manufacturers needed to get their “shit together”.

“I just don't understand that some teams concentrate more on the others and keep arguing a case that is very clear and transparent. Communication with the FIA was very positive all along and it's not only on compression ratio, but on other things too. Specifically in that area, it's very clear what the regulations say. It's very clear what the standard procedures are on any motors, even outside of Formula 1. So just get your shit together.”

He added: “The power unit is legal. The power unit corresponds to how the regulations are written. The power unit corresponds to how the checks are being done.”