Last Updated on February 7 2026, 2:49 pm

There is a row brewing in Formula One and currently the FIA appear powerless to defuse the matter. After fears abounded throughout 2025 that Mercedes would deliver the best new F1 power units, the recent Barcelona test did nothing to assuage these concerns.

The Brackley based team were the only one to rack up more than 500 laps in Span and whilst Aston Martin was scrabbling around to complete a handful of laps on the final day, Mercedes had packed up and gone home to analyse their data.

Even before the first livery reveal of the year in January, teams up and dow the paddock were accusing Mercedes of using a ‘loophole’ in the way the FIA test the new powertrains to gain an illegal advantage.

 

 

 

Furious Wolff SLAMS his accusers

It all concerns compression ratios inside the internal combustion engine. Mercedes are said to have developed cleverly designed metallurgical components which when the engine is hot expand, allow for a greater compression ratio than the 16.1 allowed by the new regulations. The FIA’s test is performed when the engine is cold and at ambient temperature.

Of course the regulation is that the compression rate should be no more than 16.1, the only issue is the FIA can’t be sure with Mercedes or anyone that this is always the case. Other manufacturers have proposed they all fit sensors to their power units which give live readings of the compression rates while the car is on track.

A furious Toto Wolff has responded to the team’s critics, when at the livery launch he was asked about the matter. The Mercedes’ team boss insisted their power unit was legal and suggested his rivals “get your shit together.” The FIA’s powertrain working party is meeting today to discuss the matter, although the FIA’s initial response has been that their hands are tied.

Now reports from Germany suggest Mercedes may have designed another clever internal engine trick to increase the compression rate, but this time if true it would be against there FIA regulations. Auto Motor und Sport now claim there are more hidden secrets to the Mercedes powertrain than just the metallurgic trick.

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Mercedes 2nd engine trick

The report suggests Mercedes have developed ‘special pistons’ by using 3D printing technology which also increase the compression ratio above the allowed 16.1. This allows a pocket to be created inside the combustion chamber which opens and closes and when closed reduces the cubic capacity of the cylinder thus increasing compression.

When the engine is being tested cold, the pocket fills up giving the correct reading of 16.1. Yet at higher temperatures the pocket becomes sealed off from the rest of the cylinder which increases the compression rate possible. AMuS claim this information has been provided by ‘other teams’ who have communicated with the FIA who confirm this trick is illegal.

In modern day Formula One, the process for designing both chassis and powertrains is almost unrecognisable when compare to how things were done just two decades ago. The team’s and manufacturers would then prepare their designs in secret with both their rivals and the FIA first seeing them when they hit the track at the start of the year.

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FIA inadvertently ‘green light’ Mercedes PU?

The teams would scrutinise each others designs to see if any rules had been bent and then report their findings to the technical arm of the FIA in the form of a protest. This led to the inevitable multiple rounds of heated debate, as the FIA tried to investigate the issues raised.

This increased the risk that numerous disqualifications would be made, after the event; something which is not a good look for any sport. Now the teams share their designs with the FIA’s technical officers during the design and build process to prevent the furore surrounding the protests from their rivals.

At each step teams and power unit manufacturers are receiving mini-rulings from the FIA on the legality of the design, but this procedure also has its downsides. In effect, the Mercedes powertrain has been declared legal along the path of its development by the FIA, something Mercedes are using as the basis of their argument ‘there’s nothing to see here folks.’

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Protests inevitable in Melbourne

Further, should the FIA find themselves hoodwinked, its much more difficult for them to declare the design is in fact now illegal, given they’ve seen the drawings and specification along the way. This is why the spectacle of a protest awaits Fomrula one when they head to the season opener in Melbourne, with Ferrari, Honda and Audi all believed to be ready to officially protest the Mercedes powertrain design.

The construction of this second theory over the illegality of the Mercedes power unit, puts the FIA under pressure because if true this would indeed be a clear matter of cheating. The teams suggesting this 2nd trick is taking place, are forcing the FIA to take another look at the disputed power unit in the hope they will uncover the metallurgical trick that Brixworth are said be employing.

One of the fundamental principles the FIA set in stone when writing the all new powertrain and chassis regulations, was there wold not be a repeat of a Mercedes’ style domination the last time new power units were introduced in 2014. Mercedes went on to win a record eight straight constructors’ titles during that era, along with seven drivers’ titles.

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Newey’s prophetic words over new F1 PU dominance

And of even greater concern will be the predictions made last year by Adrian Newey, that the 2026 regulations could see one manufacturer deliver an all dominant powertrain. “There has to be a chance that one manufacturer will come out well on top, and it will become a power-unit-dominated regulation, at least to start with,” the Aston Martin design guru told AMuS.

“There’s a chance that if it’s on the combustion engine side of it, that somebody comes up with a dominant combustion engine that will last through the length of the formula, because the way the regulations are written, it’s quite difficult for people who are behind to catch up.” Prophetic words indeed.

Regardless of the design process and the ‘green lights’ issued to Mercedes along the way, the FIA will be concerned of another era of F1 domination. And with reports suggesting the Mercedes metallurgical trick could be worth up to four tenths of a second, at some point F1’s governing body will need to respond.

One course of action would be to allow the other manufacturers to copy this design, but most analysts believe this would take around a year before their pools of engines were constructed, tested and fitted. Further, whilst the ‘spirit of the law’ is irrelevant in the hard, cold world of F1 regulations, it is embarrassing for the FIA to have overlooked such a scenario where their intentions have been blatantly overridden.

 

 

 

Brundle wary of too much “fake” overtaking in F1 new rules

As the news and opinion continues to drip out from the ‘private’ test in Barcelona, it is becoming patently clear that the new Formula One era upon us will be significantly different from anything before in the history of the sport.

A number of the drivers who have commented on how they need to adapt their driving styles to deal with the huge amount of energy management, given the new F1 power units now have to power 350kw electric motors some three times more output than previously.

This of course will require a significant amount of harvesting and energy deployment and whilst the teams may devise some algorithms to optimise where and when on the circuit this should happen, it will be the drivers who make the final decision….. READ MORE