The 2026 Formula 1 season is set to be significantly influenced by the introduction of new engine development rules, with 'ADUO' becoming a key acronym in the paddock. ADUO, or Additional Development and Upgrade Opportunities, is a provision within the F1 rules that allows power unit manufacturers to improve their engines if they are lagging behind the benchmark performer.
This regulation change is crucial, given the significant increase in electrical power to achieve a 50-50 split with internal combustion engines in the new power units introduced this season. Any new set of engine regulations often results in performance gaps among teams, which is why the rules include provisions for performance-balancing measures. ADUO specifically focuses on the internal combustion engine (ICE) part of the power unit, with the FIA measuring performance at every race using a performance index not available to the media.
Manufacturers that are two per cent or more behind the leading ICE will be granted ADUO, allowing them to develop their power unit. The grants are not cumulative within a season and are based on the first occasion a manufacturer qualifies. There is also a financial mechanism under the cost cap for power-unit manufacturers, with allowances ranging from $3m to $11m based on the performance deficit.
The FIA will review ICE performance at three points during the season, after the fifth, 11th, and 18th rounds, with results communicated no later than two weeks after each review. Manufacturers can introduce upgrades after the first review, but those supplying multiple teams must ensure they can provide the same ICE specification to their customers. While Ferrari's boss, Fred Vasseur, sees ADUO as an opportunity to close the gap to Mercedes, Toto Wolff, the Mercedes chief, has urged the FIA to ensure engine upgrades do not interfere with the competitive order. The ADUO rule is not a 'magic bullet' but provides leeway for development within the technical regulations framework.
As the season progresses, ADUO is likely to remain a topic of discussion, with manufacturers working on upgrades and the FIA closely monitoring performance to maintain a balanced competition.