Mercedes delay ADUO engine upgrade beyond Austin and Mexico, with Brazil the earliest target

Mercedes have postponed the debut of their upgraded power unit, which had been pencilled in for this weekend's United States Grand Prix. According to The Race, the engine allowed under F1's catch-up rules is not ready for Austin, is not expected for Mexico the following weekend either, and is now most likely to appear at the Brazilian Grand Prix on 8 November at the earliest.

What the ADUO engine is

ADUO stands for Additional Development and Upgrade Opportunities, a mechanism in the 2026 rules that lets a manufacturer bring a mid-season engine upgrade if its power unit is judged to be sufficiently behind the benchmark. The Race reports that Mercedes were assessed as more than two per cent adrift of the benchmark unit, which it identifies as Red Bull's, opening the door to the upgrade.

That assessment fits what rivals have been saying in Austin. Lewis Hamilton, discussing the Singapore Grand Prix, credited Red Bull with having the best engine this year and said Ferrari were three or four tenths slower on the straights.

Why the timing has slipped

The Race says Mercedes will only bring the new unit once they are sure it is a genuine step forward. With the team leading the constructors' standings by a large margin and Kimi Antonelli 102 points clear in the drivers' table after Singapore, the main value of the upgrade now lies in preparing for 2027. Even two or three weekends of running before the season ends could provide useful information for next year.

The team also has chassis work to finish. Mercedes brought a major aerodynamic upgrade at the Malaysian round at Sepang, which initially made the car slower, and they have been working through the problems since.

What it means for Russell

There is a practical cost. George Russell suffered an engine failure at Sepang earlier this month that triggered a grid penalty in Singapore, where he started from the back and recovered to ninth. Fitting the ADUO engine will bring another grid penalty for him, so the choice of venue matters.

Russell is second in the standings on 238 points, but Lewis Hamilton is only nine behind on 229 and Max Verstappen 17 behind on 221, so a penalty at the wrong track could cost him in the fight for runner-up.

Chassis upgrade on both cars in Austin

While the engine waits, both Mercedes drivers will have the upgraded chassis from first practice in Austin. In Singapore the team split the package between its two cars.

Key takeaways

• Mercedes' ADUO engine upgrade will not debut in Austin and is not expected in Mexico.
• The Brazilian Grand Prix on 8 November is the likeliest earliest debut, according to The Race.
• The team qualified for ADUO after being judged more than two per cent behind the benchmark power unit.
• Using the new engine will bring another grid penalty for George Russell.
• Both cars run the upgraded chassis in Austin.

FAQ

What is ADUO in Formula 1? It is the Additional Development and Upgrade Opportunities mechanism in the 2026 rules, allowing manufacturers judged to be behind the benchmark power unit to bring a mid-season engine upgrade.

When will Mercedes introduce the upgraded engine? Not in Austin or, according to The Race, in Mexico. The Brazilian Grand Prix on 8 November is the earliest likely debut, and only if Mercedes are convinced it is a step forward.

Will George Russell take a grid penalty? Yes, when the ADUO engine is fitted to his car. He already took a penalty in Singapore after an engine failure at Sepang.

Sources: The Race, RacingNews365, PlanetF1, Malay Mail