FIA faces fresh scrutiny as David Coulthard points to rule oversight amid compression ratio saga

David Coulthard has criticised the FIA’s rule-making after claims that Mercedes exploited a 2026 compression ratio loophole

Former Formula 1 driver David Coulthard has called out the FIA after Mercedes is claimed to have made use of a compression ratio loophole.

The compression ratio is just one of many changes introduced as part of the new 2026 regulations. Previously, that ratio stood at 18:1, but under the new regulations, the FIA has reduced it to 16:1.

It was suggested in December 2025 that Mercedes had found a way to achieve a higher compression ratio when the engine is running on track, making the most of a loophole that it is only measured when the car is static and at ambient temperatures.

It has now been proposed that a rule change could be introduced from 1 August 2026 to close the loophole. This will go to a vote of the power unit manufacturers, the FIA and F1.

It is worth noting that Mercedes team principal Toto Wolff has insisted that their engine is legal and that the design has been approved by the FIA.

Andrea Kimi Antonelli, Mercedes

Photo by: Sam Bagnall / Sutton Images via Getty Images

"Well, here's the thing. You mentioned the FIA, the Federation Internationale de l'Automobile. They are the governing body of Formula 1. And I've read recently they're going, 'Well, we're only about 20 people writing the rules and Formula 1 teams of hundreds of people, which is why we didn't figure out the loophole and then close it down,'" Coulthard explained during the Up To Speed podcast.

The former Red Bull driver added: "If the regulation makers did a better job, quite frankly, of understanding the operational window of a Formula 1 car... An operational window of a Formula 1 car isn't sitting in a garage at ambient temperature. It is out on track. The engine temperature at 110°, everything red hot, brakes at over 1000°. That's where they should be designing the rules and regulations."