Last Updated on December 22 2025, 7:52 am

There was Williams active suspension in the 1990’s, Renault’s electronic gismos in the mid naughties, the double diffuser of the Brawn car and off throttle blowing by Red Bull and Renault. All loopholes in the regulation which a single team managed to exploit to win championships.

Now with the biggest set of technical regulations coming in the history of F1, another loophole is likely to cause a paddock row and a potential protest from certain teams come the season opener in Australia.

The grey area some manufacturers of the powertrains are seeking to exploit is over the new compression ratios for the internal combustion engine specified by the FIA.

 

 

 

Maximum compression rate for ICE reduced for 2026

Whilst no formal complaint has yet been made, the finger of suspicion has fallen upon Mercedes – who supply McLaren, Williams and Alpine together with Red Bull powertrains who supply the Racing Bulls and Red bull Racing.

The beef surrounds Article C5.4.3 of the new technical regulations which mandates a reduction in compression rates from 18.0:1 to 16.0;1. The reason behind this was to temper peak performance and deliver more efficient combustion in lines with the sport’s ever increasing green values, but it appears to have created a new complex battle between the manufacturers.

The loophole has been created by the FIA’s decision on how to measure the new ratio. Under the current rules this will take place while the car is stationary and at ambient temperatures. It has been suggested engineers at the two manufactures stated have utilised designs with complex internal components that expand significantly at the higher operating temperatures on track.

This then would increase the compression rate possible beyond the stated limit from the FIA. So the combustion engine will pass the test at 16.0:1 when the engine is relatively cold whilst increasing the compression possible during track sessions.

Global boom: Why F1 is attracting more fans than ever

 

 

 

Expanding designs offer 15hp more

Rough estimates suggest this may offer an additional 15 horsepower which in terms of lap time would be an addition 2.5-3 seconds per lap, which is a huge margin. In 2025, two qualifying one sessions saw all twenty drivers within a second of each other and whilst with all new technical rules this will almost certainly expand, 0.3 seconds is not insignificant.

The matter has clearly been one the FIA have been aware of given they have amended the wording of the regulations surrounding this more than once in recent months. In October they clarified the situation stating the measurements would be “executed at ambient temperature then another guidance document demands the manufacturers detail their own measurement procedures for approval.

The FIA does understand there is a issue from potential thermal expansion, upping the compression rate but has no contingency as of yet to deal with this.

The Race have now reported a recent observation made by a spokesperson from the FIA. “The regulations clearly define the maximum compression ratio and the method for measuring it… It’s true that thermal expansion can influence dimensions at operating temperature, but the current rules do not currently require measurement under hot conditions.

Alonso teases with a vision of his third championship

 

 

 

FIA have no solution to the loophole

“That said, the topic has been and is still being discussed within technical forums with the PUMs [power unit manufacturers], as the new limit naturally raises questions about interpretation and compliance.

“The FIA continuously reviews such matters to ensure fairness and clarity, and if necessary, adjustments to the regulations or measurement procedures can be considered for the future.”

The bind for the FIA is that revising the rules and measurement procedures should a protest be forthcoming is no simple task. Even measuring the compression rates immediately after a car comes into the pits, may not uncover the full extent of the advantage that particular PU has.

Clearly the drivers would ensure their in lap was a slow as possible,  allowing the thermo expansion to reverse at least partially so the true effect of the clever technology when a car is flat out would be unknown. Once the power units have been locked in for the season, enforcing PU manufacturers to alter the architecture or components within the powertrain would be a lengthy and complex task.

How George Russell knows the writing is on the wall with Wolff

 

 

 

Rogue Mercedes engineer spills the beans

Yet without some form of definitive regulation which covers this there will inevitably be a protest against the legality of one or more of the PU’s being run by the teams. The issue allegedly came to light when an engineer left the Mercedes HPP facility in Brixworth and shared their secrets with other teams who clearly have not explored this grey area.

Mercedes like Honda have shared an audio teaser of the sound of the 2026 PU and the word in the paddock for some time has been that one again there Mercedes’ branded powertrains will be the class of the field come testing in just over five weeks time.

Ex-Maclaren and Aston Martin engineer and now Sky F1 pundit, Bernie Collins suggests that Mercedes may have a big advantage over their rivals in terms of the 2026 PU. “I think the status quo will change amongst the teams because I think it’ll be who – someone will get the engine right, and someone will get the engine wrong,” she told the F1 show podcast.

The return of the German GP: Domenicali’s thoughts

 

 

 

Mercedes expected to come out on top

“I think the perception is that Mercedes-engineered teams will rise to the top. But we don’t know. We’ve not compared them against each other. If nothing else, they’ve got three teams that they’re supplying, so they’re going to learn a lot faster than Honda, who only supply one team.”

Interestingly Toto Wolff commented earlier that come the next cycle of F1 power, Mercedes would be reducing the number of customer teams they supplied, suggesting two was the optimal number due to lead times for upgrades being shorter now the manufacturers must issue all teams with the specification of PU they run themselves.

Nobody really knows the pecking order for next season, even Aston Martin with their high powered team of Adrian Newey, Andy Cowell and Eric Cardile in partnership with Honda could emerge as the leaders of the pack come January. However, the grey area over how the maximum allowed compression is achieved and measured is likely to become a significant point of contention in just a handful of weeks time.

 

 

 

Verstappen stands by his criticism of Norris: “I clearly suffered from that”

Verstappen stands by Singapore qualifying frustration – Max Verstappen has reiterated his stance on Lando Norris following the controversial incident during the Singapore Grand Prix. During qualifying at the Marina Bay Street Circuit, the McLaren driver reportedly disrupted the Red Bull Racing driver’s final flying lap in Q3, a move that the four-time world champion insists impacted his chances of securing pole position.

In his end-of-year interview with Viaplay, Verstappen reflected on the event and reiterated that he still feels the incident was significant.

“Yes, one hundred per cent. That clearly bothered me,” said the Dutchman. “With these cars, that has become an increasingly big problem, but ultimately, that’s how it is. Otherwise, I would have been close to pole position.”…. READ MORE