What is ADUO? The FIA lifeline that could rescue Honda

As part of the F1 2026 regulation change, the FIA rolled out an ADUO concept for the power unit manufacturers which offers a safety net for any that are struggling.

In late 2025, the FIA confirmed the introduction of the ADUO concept, providing greater development opportunities for the five power unit manufacturers [PUMs] in Formula 1.

What is ADUO?

The introduction of a very different engine formula for F1 2026 has seen the retention of the 1.6-litre V6 architecture used in the last generation, but the similarities broadly stop there.

The MGU-H has been removed, while the electrical output ratio has been increased to bring a more equal split between internal combustion and the hybrid ancillaries.

Ferrari, Mercedes High-Performance Powertrains [HPP], Red Bull Powertrains [RBPT], Honda, and Audi are the five power unit manufacturers on the grid, while General Motors is scheduled to arrive as a PUM in 2029.

On March 1, the designs of these power units were submitted to the FIA for homologation, ie. the process of checking whether the power units fully adhere to all the regulatory requirements, with the designs then being sealed off.

There is scope for some development over the five years, although it is quite limited from a performance perspective. Different components of the power unit are assigned definitions under the regulations, and, depending on these definitions, the PUMs are told if, and when, upgraded parts can be introduced.

But, given the potential for huge disparities in performance between the respective offerings from the five current PUMs, the FIA saw fit to grant a safety net for any PUMs that are struggling to keep up.

This is what the ADUO concept is designed to do. The acronym stands for Additional Development and Upgrade Opportunities, which is quite self-explanatory: quite simply, any PUMs who are too far behind the bell curve of performance of the benchmark engine will be given extra opportunities to introduce new components.

How will the new ‘ADUO concept’ work?

If any PU manufacturers find themselves lagging behind the others in terms of performance, the FIA will spot these deficiencies by way of ongoing performance measurement.

Essentially, think of ADUO as a more complex, power unit-specific version of the Aerodynamic Testing Regulations that we’ve become accustomed to in recent years, a regulatory rubberbanding to ensure that no PUM ever falls too far behind through this regulatory cycle.

Manufacturers that meet certain criteria outlined in Article 4 of Appendix 4 of the new technical regulations are eligible for the additional opportunities outlined under the ADUO rules.

These allow for extra specification upgrades in both the qualifying year (Year N) and the following year (Year N+1).

Most of the power unit components have been left eligible for ADUO, aside from certain items such as the fuel pump and injectors, knock sensors, and a wide range of temperature, electrical, and regulatory sensors.

Throughout the next five years, the FIA will closely monitor the performance levels of the internal combustion engines in all the power units supplied by each manufacturer. For each engine, an “ICE Performance Index” will be calculated, utilising data and supplementary information from the manufacturers and their customer teams.

This index will be used to benchmark the PUs against each other during each assessment period and used to determine which, if any, manufacturers need the additional upgrade opportunities.

More on the F1 2026 regulations

F1 2026 explained: why ‘super clipping’ could reshape racing

Explained: F1’s complex power unit upgrade system

The on-track performance and results will have no bearing on this indexing, with the FIA’s measurements focusing on the performance output of the ICE utilising the aforementioned data, meaning that a dominant PUM wouldn’t be able to disguise its superiority by way of compromising its own on-track speed or success.

If granted, the relevant manufacturer can implement upgrades to the prescribed components, as outlined in Appendix 4, extend the usage of their power unit test benches, and make a downward adjustment in their cost cap reporting.

PU manufacturers will be granted opportunities on the following criteria:

• PU Manufacturers whose ICE Performance Index is at least two per cent but less than four per cent below the best-performing ICE will be eligible for:
  1 additional homologation upgrade in season N
  1 additional homologation upgrade in season N+1
• PU Manufacturers whose ICE Performance Index is at least four per cent below the best-performing ICE will be eligible for:
  2 additional homologation upgrades in season N
  2 additional homologation upgrades in season N+1

ADUO upgrades are not cumulative within a season and will only be granted following the first occasion that the PUM is assessed by the FIA as eligible for ADUO.

Almost all components of the power unit are upgradeable under the ADUO system.

Each season will be split into four equal-length periods, with the 24-race calendar of 2026 split into four sections of six races. At the time of writing, due to the cancellation of the Bahrain and Saudi Arabian Grands Prix, discussions are underway about whether to keep the existing ADUO checkpoint between the Miami and Canadian Grands Prix; these races are now the fourth and fifth rounds of the championship.

Manufacturers granted ADUO opportunities can introduce the updates at the first race of the following period.

For instance, any manufacturer given an upgrade opportunity after the first six races of 2026 may only introduce a new component, as defined under the criteria of Appendix 4, at the seventh round of the championship. If this opportunity is granted after the 12th round of the championship, it can be introduced at the 13th round.

To provide an example of how the ADUO could work in practice, let’s choose a component from the Appendix list of definitions.

The MGU-K is item 26 on the list and, according to the normal upgrade window, can be changed at the start of the 2028 and 2030 F1 seasons.

But, if a PUM granted a homologation upgrade at the first checkpoint believes its MGU-K isn’t up to scratch, it can introduce an upgraded MGU-K at the first race of the next window, rather than having to wait until 2028.

Any unused homologation upgrades not used during season N are forfeited.

If any changes are made to the power units by the manufacturer, whether under ADUO or standard development permissions, it must submit an updated version of its homologation dossier at least 14 days before the first race weekend in which it is used.

Some very minor prescribed updates are also permitted, on the grounds of “the sole purposes of reliability, safety, cost saving, or supply issues, subject to approval”.

Other modifications may be (but are not limited to) due to different branding, a change of supplier, a change of part number, etc., and may have no or very limited effect on reliability or functionality.

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