FIA makes final ruling on Mercedes F1 engine controversy

Formula 1 bosses have confirmed a rule change to close a loophole Mercedes is believed to have exploited in the engine regulations. 

F1’s governing body the FIA confirmed on Saturday morning that a crucial e-vote to change the rules from 1 June was “approved unanimously” by the five power unit manufacturers. 

Ferrari, Audi and Honda suspected Mercedes of having found a way to use thermal expansion to exceed the mandated compression ratio of 16:1, which was previously only measured at ambient conditions. 

Mercedes is accused of finding a way to exceed this when the engine is running at temperature. Under the regulation tweak, the compression ratio will be controlled in both and hot conditions from 1 June this year. 

It will then only be controlled in operating conditions from 2027 onwards. 

The decision is set to bring the engine compression saga to an end on the eve of the 2026 F1 season, which begins with the Australian Grand Prix next weekend. 

Originally, the proposal was set to see the new checks come in from August, but this appears to have been brought forward. 

“Amendments to the 2026 FIA Formula 1 Regulations have been approved unanimously by e-vote by the World Motor Sport Council,” an FIA statement read. 

“Some aspects of the amendments were concurrently approved unanimously by the Formula One Power Unit Manufacturers.  The modifications to the Technical Regulations follow the pre-season tests in Barcelona and Bahrain and extensive feedback received from drivers and teams.

“A significant effort has been invested in finding a solution to the topic of the compression ratio. This parameter, which was one of the key fundamental targets of these regulations in order to attract newcomers to the sport, is limited in the regulations to 16:1, measured in cold conditions. 

“The FIA has worked to find a compromise solution which determines that the compression ratio will be controlled in both hot and cold conditions from 1 June 2026, and subsequently only in the operating conditions (130deg C) from 2027 onwards.

“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.  

“Further evaluation and technical checks on energy management matters are ongoing.”

Having initially claimed that any rule change would “screw” Mercedes, team principal Toto Wolff later downplayed the engine compression ratio saga, describing it as a “storm in a teacup”.

“We said it all along that this looks like a storm in a teacup, the whole thing,” Wolff said during the final week of pre-season testing in Bahrain. 

“Numbers were coming up that were, you know, if these numbers would have been true, absolutely understand why somebody would fight it. But eventually, it’s not worth the fight.

“It doesn’t change anything for us, whether we stay like this or whether we change to the new regulations, and that’s been a process. But we also want to be good citizens in the sport because it doesn’t make a big difference.

“We then changed opinion. Philosophically, you can disagree with it, because I believe regs are there to be made and you keep the FIA close to you – and that’s how it should be.

“But, if you have four other PU [manufacturers] that are putting immense pressure on the FIA at a certain stage, what choice do we have [other] than not to play? We were pretty comfortable in even having a protest going on Friday in Melbourne. Is this what we want?”

Monaco two-stopper dropped 

It has also been confirmed that F1 has dropped mandatory two-stop format for the Monaco Grand Prix. 

The controversial rule change was introduced for the 2025 race, forcing the drivers to make at least two pit stops so that every car used three sets of tyres during the Grand Prix.

The plan ultimately failed to spice up the on-track action and led to teams in the midfield using one of their cars to strategically back-up rivals. 

Following discussions, the proposal has been scrapped altogether from 2026 onwards.