Formula 1’s ADUO rules were created to help power unit manufacturers recover performance when they fall behind the benchmark, but the consequences of that opportunity are not necessarily the same for everyone. Ferrari and Mercedes have made different technical choices with their 2026 engines, and those decisions could now mean that development permitted under ADUO offers Mercedes a more valuable long-term benefit while leaving Ferrari facing a difficult compromise.
The principle that the rules are not always equal in their practical effects may sound rhetorical, but it can also apply in Formula 1. Before considering why Ferrari may find itself at a disadvantage, however, it is important to understand the technical basis of the Additional Development and Upgrade Opportunities mechanism and the philosophy behind it.
The fundamental principle behind F1’s ADUO rules
ADUO concerns the Formula 1 power unit, although eligibility for the mechanism is determined through the performance of the internal combustion engine, or ICE. During 2025 and throughout the winter, there was extensive discussion over how much freedom the regulations should give manufacturers that had fallen behind and needed an opportunity to recover ground against rivals that had produced a stronger package.
At the time, Mercedes was widely expected to hold an advantage. Mercedes team principal Toto Wolff repeatedly addressed the subject publicly, arguing that ADUO should allow struggling manufacturers to reduce their deficit but should never enable them to completely eliminate the gap or even overtake the leading engine manufacturer. That concept became one of the fundamental principles behind the FIA’s system.
After around six months of discussion along those lines, the FIA’s measurements produced a surprise. The benchmark internal combustion engine was not Mercedes, but the unit developed by newcomer Red Bull-Ford Powertrains. The subsequent ADUO assessments gave Ferrari development opportunities as Maranello attempted to respond to its power unit deficit, a process also shaped by the long development times and budget restrictions surrounding Ferrari’s ADUO programme.
Why Ferrari and Mercedes face different ADUO consequences
That leads to the central question: why could the same ADUO regulations have different consequences depending on which manufacturer is using them? The answer lies in the underlying principle of the system and, just as importantly, in the technical choices each manufacturer made before the season began.
Mercedes and Ferrari adopted different approaches to their turbochargers. Ferrari selected a smaller turbine diameter than some of its competitors, a choice intended in part to avoid difficulties when launching the car from the starting grid. Mercedes instead opted for a larger solution, providing greater performance potential during the race but creating a significant complication when the lights went out.
The FIA subsequently introduced the much-discussed pre-start procedure, giving drivers additional time to build engine revs and spool the turbo before the normal start-light sequence begins. That intervention reduced one of the disadvantages associated with the Mercedes concept, while Ferrari had originally gained from its more responsive turbo arrangement.
The differing philosophies have become particularly significant during Ferrari’s recent development work. The team’s latest programme included a second ADUO turbo development centred on changes to the compressor and turbine package, as engineers searched for further performance without completely transforming the architecture of the 2026 power unit.
Ferrari’s ADUO advantage becomes a potential limitation
Ferrari cannot, according to the regulatory limitation at the centre of this argument, simply use its current ADUO opportunity to increase the turbine diameter. Even leaving the regulations aside, attempting such a substantial modification during the championship would be an extremely demanding engineering exercise.
Increasing the dimensions of a major component and then fitting it beneath bodywork and into an installation originally designed around the previous specification would require extensive work. It would be expensive, would involve several technical departments and could have consequences for packaging far beyond the turbocharger itself.
Ferrari therefore limited its second ADUO step to changes including the angle of the turbine blades and several additional improvements that appear to have generated approximately five to six horsepower. The wider implications of those changes became especially relevant at Monza, where the SF-26 power unit upgrade involved more than simply chasing peak horsepower.
For Ferrari, however, spending resources on these relatively small gains carries an additional frustration. Once the season concludes on 6 December, the current concept is likely to be discarded or substantially revised as Maranello turns towards hardware that could be significantly different in several respects.
The latest specification has nevertheless provided useful information. Ferrari’s ADUO2 unit survived Charles Leclerc’s heavy accident at Monza, although the team decided not to use that particular engine in Madrid, as explained in our update on the condition and future use of Charles Leclerc’s ADUO2 power unit.
Why Mercedes could benefit more from its 2026 development
Mercedes does not face exactly the same problem. The engineers at Brixworth may also be restricted to relatively small improvements in some areas of the ICE, but the key difference is that the 2027 specification is expected to be a direct evolution of the 2026 power unit.
That means even a modest step made during the current season can contribute directly to Mercedes’ progress next year. The manufacturer can continue building on the knowledge accumulated with its existing architecture rather than preparing for a potentially more fundamental change of philosophy.
In that respect, Mercedes is in a particularly favourable position. Much of the technical know-how generated in 2026 can continue to be exploited, while Ferrari may not enjoy the same level of continuity. For broader developments surrounding the rival team, Mercedes’ Formula 1 programme remains one of the key technical reference points of the current season.
Ferrari’s 2027 power unit could require new compromises
If Ferrari ultimately chooses to move towards a larger turbo for 2027 – something that remains a possibility rather than a confirmed decision – Maranello will have to identify a new set of compromises. Those would concern not only the internal combustion engine but probably also the way electrical energy is stored, deployed and managed throughout a lap.
A different turbo philosophy could alter several characteristics of the power unit package, forcing Ferrari to establish new operating references rather than simply refining everything it has learned during 2026. Some of the knowledge accumulated with the current configuration would remain valuable, but other parameters could have to be reassessed.
That is what makes the comparison with Mercedes particularly significant. Both manufacturers can use ADUO to pursue performance, but the value of each improvement depends heavily on where their respective technical projects are heading. Mercedes can potentially turn its present development into a foundation for 2027, while Ferrari may be spending part of 2026 optimising an architecture it could substantially change only months later.
For Maranello, the challenge is therefore not simply to find more horsepower before the current season ends. Ferrari must extract whatever performance is still available from the present package while ensuring that short-term development does not distract from the much larger task of defining a stronger and more sustainable power unit concept for 2027.
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