Five F1 engine manufacturers to vote on rule change after Mercedes accused of exploiting regulation loophole to their advantage.

The FIA is putting a change to compression ratio measurement for 2026 to a vote among the five Formula 1 engine manufacturers. Mercedes has been accused of exploiting a regulatory loophole by only having to measure the prescribed 16:1 ratio when the engine is cold.

The proposed rule change would require additional measurements at 130°C operating temperature from August 2026. Mercedes now stands isolated – even Red Bull Powertrains now supports the rule clarification. The voting result is expected within ten days.