Mercedes team principal Toto Wolff has called on the FIA to ensure the new ADUO development windows for 2026 do not upset the current competitive order in Formula 1.
The regulations allow Additional Development and Upgrade Opportunities (ADUO) during three specified periods of the season. Any power unit manufacturer judged to be at least 2% slower on the internal combustion engine compared with the leading unit can be granted development chances to catch up.
The FIA is expected to clarify how those thresholds and decisions will be applied ahead of the Miami Grand Prix (May 1-3). Mercedes enters that weekend after winning the opening three races and leading the standings, so their in-house engine is the likely benchmark for any catch-up assessments.
Wolff stressed that ADUO was designed to help teams that are behind recover ground, not to let them leapfrog rivals. He urged the regulator to apply the rules with absolute precision, clarity and transparency, warning that gamesmanship should have no place in the process and that the FIA must act in the right spirit.
He suggested Honda, which now supplies only Aston Martin, appears most likely to need assistance, while other manufacturers are broadly similar in performance. Wolff added he would be surprised and disappointed if ADUO decisions resulted in any interference with the sport’s existing pecking order.
Context: Mercedes is a works team and supplies engines to McLaren, Alpine and Williams. Ferrari is a works operation supplying Haas and Cadillac. Red Bull developed its own 2026 power unit and supplies junior team Racing Bulls. Audi remains a works-only manufacturer without customers.
Ferrari team principal Fred Vasseur has said ADUO could be an avenue for his team to close the gap to Mercedes. Wolff said he is not personally worried about Ferrari jumping ahead but noted teams are closely watching how the FIA makes ADUO calls. Mercedes has detailed analytics on rival engine performance, and Wolff again urged the FIA to protect the integrity of the championship by ensuring ADUO remains a catch-up measure, not a way to reshuffle the order.