The FIA ADUO review is nearly done, and the news is not what Red Bull were hoping for. According to The Race, the governing body’s investigation is set to confirm its original finding: that Red Bull Powertrains holds the best internal combustion engine in Formula 1 for 2026. That means no upgrade opportunities for the Milton Keynes team, while every other manufacturer gets to work improving their power units.
What Is the FIA ADUO Review?
ADUO stands for Additional Development and Upgrade Opportunities. The system was introduced to prevent manufacturers from falling irretrievably behind under Formula 1’s tightly controlled engine regulations. In simple terms, if your engine is behind the best one, you get permission to improve it.
ADUO will be granted to manufacturers who are down on performance to the leading ICE by two per cent or more. Manufacturers trailing by between two and four per cent will be granted one opportunity to develop their power unit this season and one more next, while those trailing by four per cent or more will get two opportunities for improvement in 2026 and two further in 2027.
Crucially, the FIA’s ADUO ranking is made taking into account the internal combustion engine only, with the powerful battery and regeneration capabilities not included in this system. That matters a lot, because Mercedes has dominated races partly thanks to its superior electrical performance.
Why Is Red Bull Unhappy With the ADUO Finding?
Given the general consensus in the paddock that Mercedes boasted the benchmark engine after dominating the start of the 2026 campaign, the news sent shockwaves through the F1 paddock.
Red Bull team principal Laurent Mekies said at the Barcelona Grand Prix that all the data the team had gathered over the early races showed that championship leader Mercedes was a step ahead in engine performance.
“Where we certainly would like to have a deeper conversation is because we do not see one single data sample that indicates that we would have an advantage over our friends at Mercedes,” he said.
The FIA agreed to carry out a review of the numbers following Red Bull Powertrains questioning the findings. The intention of the review is to verify the results, and the FIA will check all sensors were functioning correctly and ensure its analysed data is accurate.
You can read more about the upgrades Red Bull brought to Austria and how the team has been trying to stay competitive throughout this difficult stretch of the season.
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What the FIA ADUO Review Is Expected to Conclude
The Race understands that the review is now nearing its conclusion but there is no indication that the FIA’s initial findings, of Red Bull being at least 2% clear of Mercedes, were incorrect. It means the result is set to remain as was officially declared by the FIA in signed correspondence sent to teams on race day at the Monaco GP.
While some final points are still being discussed with Red Bull, it is anticipated that the FIA will officially announce the ADUO findings at some point before the Belgian Grand Prix next month.
Meanwhile, Mercedes are deemed to be more than two per cent behind Red Bull’s power unit, so will be given one engine upgrade this year, while Ferrari, Audi and Honda will be given two upgrades as they are deemed to be more than four per cent adrift of Red Bull.
Looking Ahead: What Does This Mean for Red Bull?
Red Bull’s hopes of qualifying for ADUO during the second review period, which runs from Monaco until the Hungarian GP, will rest on whether Mercedes makes any performance steps with its internal combustion engine.
If Mercedes elects to stand still, or develop other parts of its power unit, then Red Bull could find itself trapped with the best ICE yet again, which would mean another spell of being unable to bring significant upgrades.
It is a frustrating situation for a team that has struggled for overall pace this season despite holding the so-called “best” engine. Check out how things have looked at recent race weekends with our reports on Austrian GP free practice and the FP1 session from Spielberg. The next ADUO review point comes after the Hungarian Grand Prix, so stay tuned. This story is far from over.
