Find out whether Ferrari, with the ADUO system, can really replicate the alleged “Mercedes trick” on the compression ratio of the 2026 power unit, and what changes with the new FIA checks.
The controversy surrounding the alleged “Mercedes trick” in the compression ratio has led to new FIA tests starting from June 2026. We analyse what Ferrari can do with the ADUO system and why it is not simple to “copy” solutions that must be approved by the Federation.
Can Ferrari really copy the alleged “Mercedes trick”?
In recent months, the Formula 1 paddock has found itself at the centre of a lively technical debate linked to the compression ratio of the internal combustion engines introduced with the 2026 power units. Some insiders have suggested that Ferrari could try to replicate a solution similar to the one hypothesised for Mercedes, but in light of the technical regulations and recent FIA decisions it seems difficult for this to happen simply through the use of ADUO.
The dispute over the compression ratio
The 2026 technical regulations state that the geometric compression ratio of the internal combustion engine must not exceed 16:1 during all phases of a race weekend. However, in recent months some teams have argued that Mercedes (and to some extent Red Bull Powertrains as well) may have found a regulatory interpretation that allows them to comply with the limit when cold, but to exceed it under real operating conditions, taking advantage of the thermal expansion of components.
This interpretation triggered protests from Ferrari, Honda and Audi, which requested clarification from the FIA, arguing that the power units must respect the limit “at all times”.
New FIA tests from June 2026
The official response from the Federation came with an update to the verification procedures: starting from 1 June 2026, the compression ratio will be checked both at ambient temperature and at operating temperature (around 130°C). The aim is to eliminate any possible technical grey area and verify that the engine does not exceed the limit even when hot.
This regulatory change was introduced precisely to prevent configurations that are only compliant when cold from being considered legitimate when the engine is in operation.
What changes for Ferrari and ADUO
ADUO (Additional Development and Upgrade Opportunities) is the mechanism introduced in the 2026 power unit regulations to allow a manufacturer that is behind to obtain additional development opportunities and bench testing time, within the homologation cycle.
However, ADUO does not mean free development: every modification must be declared and approved by the FIA before being introduced on track. Updates allowed through ADUO typically include:
- fuel and engine oil with approved specifications;
- optimisations of electronic management, software and mappings;
- small structural or material adjustments through amendments to the homologation dossier.
There is no possibility to rethink or redesign the internal combustion engine or critical components in a way that creates a functional “trick” related to the compression ratio, as these changes fall under the initial homologation scope and require a formal update of the dossier.
Why Ferrari cannot simply “copy” Mercedes
There are two key points:
1. Engines must comply with the regulations in all conditions.
The 16:1 limit is no longer measured only when cold, but also when hot after the new FIA tests from June 2026. This means that any attempt to achieve a value above the regulatory threshold through thermal expansion risks being penalised if it does not comply with the new measurements.
2. Any substantial modification to the power unit requires FIA approval.
The regulations require that any major change to the structure or components of the power unit must be submitted as a homologation update and reviewed by the Federation. It cannot be implemented arbitrarily through ADUO.
This makes it extremely complex – if not practically impossible – for Ferrari to introduce significant solutions similar to those discussed in relation to Mercedes, without first obtaining approval and passing the new FIA tests.
Conclusions
In light of the regulatory changes and the current technical framework, Ferrari cannot simply replicate an alleged “Mercedes trick” using ADUO. The permitted modifications must be approved and must comply with much stricter checks, particularly regarding the compression ratio, which is now verified also under hot conditions.
The early-season technical dispute and the update to verification procedures from June show that the FIA is aiming to definitively clarify the rules, eliminate grey areas, and ensure that all manufacturers comply with the limits set by the regulations.
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