The 2026 Formula 1 season will be defined by the new Additional Development and Upgrade Opportunities rule, known as ADUO, which lets power‑unit manufacturers tweak their internal combustion engines if they fall two per cent or more behind the benchmark. The regulation arrives alongside a 50‑50 split between electric and ICE output, the biggest technical shift in recent memory. Teams will watch the secret index.

Mercedes has already set the early pace, winning the opening three rounds and establishing a clear ICE benchmark. Ferrari boss Fred Vasseur argues that ADUO offers a legitimate path to close the gap, while Toto Wolff warns the FIA formally to prevent upgrades that could reshuffle the current pecking order. The FIA will review performance after rounds six, twelve and eighteen.

If a manufacturer trails by four per cent or more, it receives two upgrade windows; those between two and four per cent get one. The timeline, originally set for a Canadian‑Grand‑Prix debut, may shift after the Bahrain and Saudi rounds were cancelled. Regardless, ADUO will shape the championship battle this year in the near term.