The FIA has officially amended the 2026 Formula 1 regulations following months of controversy linked to the Mercedes engine case. After intense debate within the paddock and discussions between manufacturers, the Federation has now confirmed the changes that will come into force starting from the 2026 season, reshaping key aspects of the power unit regulations.
The matter had been under discussion for several months. Following a crucial meeting held during pre-season testing in Bahrain and an online vote involving all the relevant stakeholders, the FIA decided to formally revise the regulatory framework in order to put an end to the controversy surrounding the Mercedes power unit. The updated rules clarify how engine compression ratios must be measured and introduce additional requirements that will apply during the 2026 championship.
The FIA updates the regulations after the Mercedes engine case
One week before the first free practice session in Melbourne, scheduled for Friday 27 February, the Federation published a revised version of this season’s technical regulations. A quick review of the document immediately highlights the modifications, which have been clearly marked to ensure full transparency and visibility for teams and manufacturers.
The following articles have been amended:
Article C5.1.18: “Treatment of numerical values: unless otherwise specified, all specific numerical values indicated in Article C5 shall be static values at room temperature.”
Article C5.4.3: No engine cylinder, as defined in Article C5.1.3, may have a geometric compression ratio greater than 16.0:1, measured under the following conditions:
– Until 31 May 2026: when the engine is at room temperature.
– From 1 June 2026 to 31 December 2026: when the engine is at room temperature and when the engine is at 130°C.
– Any component, assembly, mechanism, or integrated arrangement of components designed or operating to increase the compression ratio under operating conditions beyond 16.0 is prohibited.
– The procedure used to assess compliance with this article must be defined by each Power Unit manufacturer in accordance with the detailed instructions set out in FIA-F1-DOC-042. This procedure must be approved by the FIA Technical Department and included in the PU manufacturer’s homologation dossier. (Note: FIA-F1-DOC-042 will be revised in accordance with the requirements that will enter into force on 1 June 2026. Consequently, the procedure will be updated and the homologation dossier amended accordingly.)
The request to introduce “hot” compression ratio tests starting from 1 June – rather than from August as initially suggested – has therefore been approved. This adjustment could have significant implications for power unit performance across the grid. It will now be particularly interesting to evaluate the potential impact on the Mercedes Power Unit and to understand whether any performance changes could emerge as early as the Monaco Grand Prix.
The FIA’s rapid response to the Mercedes engine controversy highlights the extreme technical sensitivity of the 2026 regulations. By moving the “hot” testing deadline forward to June 1st, the governing body is attempting to close potential loopholes regarding thermal expansion and compression ratios before they can define the championship outcome. For Mercedes, this accelerated timeline represents a significant engineering challenge, as any performance advantage gained through these specific parameters must now be strictly validated under high-temperature conditions much sooner than expected.
