FIA Approves Compression Ratio Rule Change Following Mercedes Engine Dispute

Posted : 28 February 2026

Mercedes’ rivals have successfully pushed for a technical rule change after a pre-season debate regarding engine performance. Audi, Ferrari, Red Bull, and Honda argued that Mercedes may have gained an advantage through innovative use of materials technology, prompting the call for adjustments to the compression ratio regulations.

The FIA confirmed on Saturday that the method for measuring the compression ratio will be revised from 1 June, with a further update planned for the 2027 season. The rule change received unanimous approval from all power-unit manufacturers.

The compression ratio measures the cylinder displacement between the extremes of a piston stroke, with increases generally translating to more power. While some estimates suggested Mercedes’ advantage could be around 0.3 seconds per lap, team principal Toto Wolff downplayed the gain, describing it as “a few horsepower – in England you would say a couple, which is more like two or three.”

Under the original 2026 regulations, the ratio was capped at 16:1, down from 18:1 under the previous rules, and measured at ambient temperature. Mercedes’ rivals had requested the measurement to be taken at operating temperature, believing Mercedes had developed a more effective method to limit thermal losses, as compression ratios typically decrease with engine heat.

Senior F1 insiders told BBC Sport that Mercedes engines complied with the 16:1 limit at both ambient and operating temperatures. Starting 1 June, the FIA will measure compression ratios at 130°C as well as ambient temperature, with next year’s regulations focusing solely on the 130°C measurement. This change allows manufacturers to exceed the 16:1 ratio at ambient temperature while maintaining the 2026 rules’ intent to attract new entrants.

The updated regulations have already influenced manufacturer decisions, with Audi and Ford entering F1 under the new power-unit rules and Honda reversing its earlier decision to exit the sport. These regulations feature an approximate 50-50 split between internal combustion and electrical power, designed to appeal to new participants.

The FIA added that significant effort had gone into resolving the compression ratio issue. “The regulations introduced for 2026 represent one of the biggest changes in recent memory. All parties acknowledge that with the introduction of such significant regulatory changes, there are collective learnings to be taken from pre-season testing and the initial rounds of the 2026 championship,” the statement read.

The governing body also noted ongoing technical evaluations on energy management, a topic of debate after drivers reported that limited energy deployment forced counter-intuitive driving techniques. Proposals are being considered to simplify energy management and ensure optimal performance under the new rules.

FIA Approves Compression Ratio Rule Change Following Mercedes Engine Dispute

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