The FIA's ADUO (Additional Development and Upgrade Opportunities) announcement at the Monaco Grand Prix revealed Red Bull Ford Powertrains as having F1's top-ranked engine. Red Bull expressed dissatisfaction with the results, even involving Oliver Mintzlaff, but could only request a factual review. FIA director Nikolas Tombazis confirmed measurements were correct, while Red Bull team principal Laurent Mekies argued there was 'not a single data point' showing Red Bull's superiority, citing deficits at power-sensitive tracks.

The ADUO system only measures internal combustion engine power output, ignoring energy management factors. Mercedes falls into the 2%-4% deficit category, earning one 2026 and one 2027 upgrade. Ferrari, Audi and Honda are in the plus-4% category, receiving two upgrades each for current and next year.

Red Bull's position was confirmed after the second ADUO period issued no additional tokens, suggesting they remain at the top or within 2% of the best. Honda chief engineer Shintaro Orihara stated the FIA's numbers were 'reasonable' and fair, noting ADUO enables their engine development efforts.