ADUO: Red Bull seeks FIA review after emerging as Formula 1's power unit benchmark

Teams and power unit manufacturers were informed of the outcome during the Monaco Grand Prix weekend. Under the ADUO system, manufacturers judged to be behind the benchmark are granted extra development opportunities to help close the gap during Formula 1's new power unit era.

According to the results, Red Bull Ford Powertrains topped the internal combustion engine rankings. Mercedes was found to be between 2% and 4% behind, making the German manufacturer eligible for one additional upgrade this season and another in 2027.

Ferrari, Audi and Honda were assessed as being more than 4% behind on ICE performance, entitling each manufacturer to two additional upgrades this year and two more next season.

Although the findings have been widely discussed throughout the paddock, the FIA has yet to publish the official results despite previously indicating that the first ADUO outcome would be released within two weeks of the Canadian Grand Prix.

The delay stems from Red Bull's request for an additional review of the data and measurement process.

Motorsport.com reports that the FIA began the verification exercise on Monday and expects the process to take between one week and ten days. While manufacturers cannot formally protest ADUO outcomes, the review allows the governing body to verify that all sensors operated correctly and that the collected data is accurate.

Only once those checks are completed will the FIA release the official figures. The request is notable because the results place Red Bull at the top of the ICE rankings, meaning it receives no additional development opportunities while its rivals gain valuable upgrade allowances.

However, the controversy surrounding ADUO extends beyond the accuracy of the measurements themselves.

The biggest criticism centres on the way the system measures performance.

ADUO assessments focus solely on internal combustion engine output. Yet manufacturers that qualify for additional development opportunities are allowed to upgrade not only the ICE but also electrical components such as the battery and MGU-K.

That distinction has raised concerns across the paddock.

If the current results are confirmed, Red Bull may possess the strongest combustion engine, but many insiders believe Mercedes still has the most complete power unit package when electrical performance is included.

Under the current rules, Mercedes would still qualify for additional development opportunities despite already being regarded by many as the overall benchmark.

That outcome appears contrary to the original purpose of ADUO, which was designed as a catch-up mechanism rather than a tool for already competitive manufacturers to extend their advantage.

FIA single-seater director Nikolas Tombazis explained that manufacturers themselves supported the simplified measurement method during discussions in 2025.

Tombazis said: "In the spring of 2025 we had quite long discussions with them. We offered whether we wanted to consider certain things like the turbo pressures, or the turbo diameters, or the plenum operating temperature and such. And the universal position by the PU manufacturers back then was that we should keep it simple.

"So the fact that it is the current horsepower measurement of the internal combustion engine has been appreciated right from the start. I would personally be quite open to the idea of complicating the parameters a bit, but that discussion was had more than a year ago and it was quite clear what it concluded."

Acoording to the Motorsport report, second concern is the potential for strategic behaviour under the ADUO framework. Manufacturers cannot accumulate unused upgrades, but the lead times involved in developing and introducing updates create opportunities to influence future assessments.

If Mercedes or Ferrari decide not to deploy all of their permitted upgrades before the next evaluation point, Red Bull could remain the benchmark at subsequent assessments. That would leave Red Bull once again ineligible for additional development opportunities while rivals continue benefiting from the catch-up mechanism.

The FIA cannot easily address those structural issues in the short term. For now, its focus remains on ensuring the accuracy of the first ADUO results before they become public.

Once the review is complete, the findings could spark a broader debate about whether Formula 1's new engine equalisation system is measuring the right performance indicators and delivering the competitive balance it was designed to achieve.