James Vowles warns ‘political’ engine row could sideline eight Mercedes cars

James Vowles has declared the compression ratio controversy in the build-up to F1 2026 is “already political” with rivals manufacturers standing together against Mercedes.

But while it appears to be four against one, he warned that changing the wording of the regulation would rule eight cars – the Mercedes-powered teams – out of the Australian Grand Prix.

James Vowles: I maintain our PU is a completely compliant

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Formula 1’s new era, both for chassis and power unit, has begun with a controversial bang amidst reports that Mercedes, and potentially Red Bull Powertrains, found a loophole in the wording of the engine regulation relating to compression ratio.

This year, the ratio has been reduced from 18:1 to 16:1 when measured in “ambient” conditions. But Mercedes, it’s been claimed, has found a way to increase the ratio to 18:1 when the engine reaches operating temperature.

Rival manufacturers are keen to end any advantage Mercedes may have gained through the loophole.

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However, for Williams team boss Vowles, it is not an advantage, its innovation, and Formula 1 should not punish teams or engine manufacturers for finding the best solution.

“Am I worried it’s political? I mean, it’s already political,” he told PlanetF1.com and other media ahead of Wednesday’s running in Bahrain.

“But my largest concern is this, we as a sport need to take care that what we’re still doing is acting as a sport, and what I mean by that is we’re not punishing the best solutions. That’s not why I joined here. It’s about meritocracy.

“At the end of the day, is there pressure? Absolutely there is pressure. But my line and Mercedes line is absolutely identical on this one. Great work by everyone across the last two years, not the last few months, last two years. That’s the result of what we have right now.

“We’re here as a sport to make sure we reward innovation, that includes, in the past double diffusers and all the other bits that have come out. This, in my opinion, is just a part.”

Asked if he had sought reassurances from Mercedes about the legality of the PU, Vowles replied: “I’m satisfied on the legality to regulations. What Toto [Wolff], myself and Hywel [Thomas] are doing is talking every few days, but that’s natural. That’s happened, whether it’s compression ratio or not, across the last few months.

“Whilst we are a customer, and we have to recognise we’re a customer that works team on this one, it is still an embedded relationship to make sure that we as teams are united on the key points.”

It has emerged that Mercedes’ rivals, initially Ferrari, Honda and Audi but now said to include Red Bull Powertrains, are pushing for a change to the way engine compression ratio is measured.

A report by The Race has claimed that Mercedes’ competitors want a change in how the compression ratios are measured when the engine is hot. This could be done by either using sensors when the cars are out on track or taking measurements in the garage when engines reach operating temperature.

And they want it implemented before the teams go racing in Melbourne in the first week of March.

Vowles, however, explained why that is easier said than done.

“There’s two points,” he said. “First of all, they have to come up with a regulation. And good luck with them, where you’re testing power units and the conditions you’re trying to run on track.

“Now, anyone that knows anything, even if you’ve done your own cars, about compression ratios is, you kind of want to do it when it’s ambient. But anyway, next, I’m sure they can determine a way of testing it.

“But the next element of things is there are now two or more steps. One, are we compliant even with any future regulation changes? No one knows that one particularly.

“And the second element of things is, what you do when you have effectively changed the rules that now mean, if we are not legal to it that there are eight cars not participating on the grid.

“And that’s what I meant by we have a sport have to really think about what this implication of these changes.”

With the compression ratio controversy stemming from the wording of the FIA’s regulation, Vowles insists motorsport’s governing body cannot be blamed as the teams “expressly” set out to find loopholes in the interpretation.

He continued: “To defend the FIA, the FIA have a hard job. You have teams filled with 1000 individuals thinking about how, I mean, expressly, we can interpret the rules in a clever way. That’s what teams do. That’s why we love the sport, and it is difficult. There’s 20 odd people trying to fight against 10,000 probably not that amount. People get the idea behind it.

“I think the FIA do a really good job, generally speaking, of finding the boundary between clever interpretation and allowing it to go forward.

“What I’m stating here is we need to take care that it’s not just politically driven by other teams that didn’t think of clever regulations now. The FIA’s job is to take a correct line of action on all this, I think they genuinely do so.

“It’s not that I think the FIA have done anything particularly wrong. I think the noises you’re hearing, for the most part, are not the FIA for teams.”

The Williams team principal, whose team would benefit from any advantage Mercedes finds, is adamant the Mercedes PU is legal.

“My harsh line on it is the PU that we have in the car is completely compliant with the regulations,” he said. “It is not a month of work, but several years of work to produce the PU to that level. And we as a sport have to take care that this is a meritocracy where the best engineering outcome effectively gets rewarded as results, not punished as results.

“I’m sure other teams are pissed off they weren’t able to achieve what Mercedes did. But we also need to take care of right now. I don’t think there’s a person in the pit lane that can tell you what is the best for you.

“My hope is the sense prevails, and that we as a sport recognise that we are here to be a metric. The best engineering solution wins as a result of it, and therefore we are where we are. But I maintain our PU is completely compliant.”

Additional reporting by Thomas Maher

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