F1 | Controversy erupts over ADUO engine rankings as manufacturers push to scrap the system. The FIA’s ADUO verdict has sparked controversy after Mercedes qualified for engine development concessions.

The FIA’s ADUO verdict has placed Mercedes within the first performance deficit bracket, a decision that has triggered widespread debate among both Formula 1 fans and power unit manufacturers. While discussions are already underway about whether the system should be revised or even abandoned altogether, Ferrari is reportedly evaluating a completely new engine concept for 2027.

The initial ADUO assessments identified the Red Bull Powertrains-Ford unit as the benchmark internal combustion engine on the grid. As a result, the Milton Keynes-based manufacturer will not be allowed to make performance-related modifications to its power unit before 2027 unless significant regulatory changes are introduced.

The biggest surprise, however, was Mercedes’ inclusion within the ADUO framework. According to the reported figures, the German manufacturer falls into the 2% performance deficit category, making it eligible for development concessions. That outcome represents a significant challenge for rivals hoping to close the gap, particularly Ferrari.

Ferrari is believed to have been classified beyond the 4% threshold, which would grant the Scuderia two development tokens for the current season and two more for 2027, along with additional budget-cap allowances and extra dyno testing time. Audi is also believed to fall within the 4% to 6% category, while Honda appears to be further behind, potentially within the 6% to 8% range.

Those classifications determine the level of support available to each manufacturer under the ADUO regulations, but the controversy now centres on how those performance gaps are actually measured.

Ferrari could now accept the 60/40 split and pursue a completely new power unit

The ADUO system evaluates only the performance of the internal combustion engine, excluding electrical energy deployment and all hybrid-related elements of the power unit. Yet those components are widely considered crucial to overall performance under the current Formula 1 regulations.

Following the publication of the verdict, discussions have intensified regarding the validity of the evaluation method itself. According to reports from The Race, the outcome could lead to requests either to abandon the ADUO system entirely or to modify the measurement criteria so that other areas of power unit performance are included in the assessment.

FIA Single-Seater Director Nikolas Tombazis previously revealed that the governing body had proposed a more sophisticated evaluation procedure, but the idea was rejected by the manufacturers.

Now, however, some parties may be reconsidering their position. The FIA has already signalled a willingness to revisit the methodology if there is sufficient support among manufacturers.

“Personally, I would be quite open to making the parameters a little more complex,” Tombazis said last April.

At Maranello, there had been hopes that Mercedes would not qualify for ADUO concessions. That expectation was one of the reasons Ferrari strongly opposed the proposed return to a 60/40 split between internal combustion and electric power for the 2027 regulations.

Given the latest situation, however, Ferrari could soften its stance. Rather than focusing exclusively on upgrading the current power unit, the Italian team may now choose to accept the proposed regulatory changes and instead concentrate its resources on developing an entirely new engine concept for 2027.