ADUO in F1: What is the engine regulation that could define course of 2026 Formula 1 season?
The term ADUO is an acronym you will be hearing a lot more about this year, so what is it and how important of a factor will it be in 2026?; first review of engine performance to take place by the FIA after the Canadian Grand Prix
Wednesday 20 May 2026 12:11, UK
With 'ADUO' set to become one of the most frequently used acronyms in the Formula 1 paddock during the 2026 season, Sky Sports F1 explains why the sport's new engine development rules are fast becoming a hot topic.
In what was widely considered to be the biggest regulation change in the sport's history, the introduction of new power units, along with new chassis, saw electrical power increased to share a 50-50 split with internal combustion engines.
Any new set of engine regulations is likely to produce gaps in performance, which is why the rules included the potential for performance-balancing measures.
- Toto Wolff urges FIA to prevent engine upgrades altering F1 pecking order
- F1 2026 calendar | F1 2026 standings | F1 gossip column
- Download the Sky Sports app for expert analysis, best video & more📱
- Not got Sky? Get Sky Sports or stream with no contract on NOW📺
Additional Development and Upgrade Opportunities (ADUO) is a part of the F1 rules specifically relating to power units, giving the five manufacturers the potential to improve their models, should they be lagging behind the benchmark performer.
The merits of the provision are already evident, given that Aston Martin, a team that was expected to be competitive, are struggling at the back of the field due to extreme issues with their Honda power unit.
Without ADUO, they could have been confined to being backmarkers all season, but the opportunity to upgrade their engine provides hope they can move forwards during the campaign.
However, while no one is questioning whether Honda should be allowed to improve their power unit, a dispute is developing over whether the other manufacturers - Ferrari, Red Bull and Audi - should be given the opportunity to bring their performance closer to that of the Mercedes power unit that has set the early benchmark.
Ferrari boss Fred Vasseur has spoken about ADUO being an opportunity to "close the gap" to Mercedes, but Silver Arrows chief Toto Wolff this week urged the FIA to ensure engine upgrades do not interfere with the competitive pecking order.
In an explanation of the rule in May, the FIA's single-seater director Nikolas Tombazis said: "It's not a magic bullet, or like the FIA is handing out brownie points to somebody who's behind, it simply provides them with leeway to develop their power unit within the framework laid out by the technical regulations."
How does ADUO work?
ADUO focuses on the performance of the non-electrical half of the power unit, the internal combustion engine (ICE).
The FIA is measuring the performance of the power units at every race using a performance index that is not available to the media.
That index is based on factors including input shaft torque, engine speed, MGU-K power and a weighting to account for power sensitivity on lap time across measured laps.
ADUO will be granted to manufacturers who are down on performance to the leading ICE by two per cent or more.
Manufacturers trailing by between two and four per cent will be granted one opportunity to develop their power unit this season and one more next, while those trailing by four per cent or more will get two opportunities for improvement in 2026 and two further in 2027.
ADUO grants are not, however, cumulative within a season and will only be granted on the first occasion a manufacturer is deemed to qualify.
There is also an accompanying financial mechanism to the rule under the cost cap for power-unit manufacturers.
Manufacturers judged to be 2-4 per cent behind will get allowances up to $3m; from 4-6 per cent behind it is $4.65m; from 6-8 per cent it is $6.35m; from 8-10 per cent it is $8m and, in a newly-added additional bracket, it is $11m for manufacturers with a deficit of 10 per cent or more.
For the 2026 season only, any manufacturer judged to be at least 10 per cent behind can further boost development by anticipating up to $8m of future cost-cap periods.
The results of the opening four rounds, each of which have been won by the Mercedes works team, suggest the Silver Arrows' self-made engine will be the benchmark.
There has been speculation that despite being well off the pace overall, Red Bull's ICE performance is actually strong, and they are unlikely to be more than two per cent behind Mercedes, or not necessarily behind them at all.
When is ADUO measured and implemented?
Ahead of the season, the FIA announced there would be three points during which ICE performance would be reviewed - after the sixth, 12th and 18th of the 24 scheduled rounds.
However, the FIA revised the timeline after what were scheduled to be rounds four and five in Bahrain and Saudi Arabia were cancelled because of conflict in the Middle East.
The three ADUO windows will now open up after the season's fifth (Canada), 11th (Hungary) and 18th (Mexico) rounds.
The results of the first review will be communicated no later than two weeks after the Canadian Grand Prix, meaning manufacturers granted ADUO could theoretically be able to introduce upgrades as early as the Monaco Grand Prix on June 5-7.
While manufacturers were set to be free to implement upgrades immediately after the first review, those supplying multiple teams would have to ensure they could provide a sufficient number of engines.
For example, Ferrari, who supply engines for Haas and Cadillac, would need to offer their customers the same ICE specification they would have for themselves, to be allowed to introduce the upgraded model.
This creates a greater challenge than for, say, Audi, who are only building their own engines.
Will manufacturers already be working on upgrades?
Yes! The two weeks between the Canadian Grand Prix and Monaco Grand Prix, for instance, would not be long enough for a manufacturer to design and produce upgrades.
They would have been working on improvements since submitting their first models for the start of the season.
Vasseur's comments suggest all four of Mercedes' rival manufacturers are anticipating being granted ADUO and therefore will likely have been aiming to have new elements ready to go.
Even Mercedes will be working on developing their engine, given that all the manufacturers are able to introduce upgrades for the 2027 regardless of their standing in the pecking order.
It is also worth remembering that any manufacturer will be able to make upgrades to all parts of their power units - including both the ICE and the electrical elements - should they be able to prove to the FIA that the changes are for the sole purposes of reliability, safety, cost-saving or supply issues.
Why could ADUO become a controversial topic?
While Vasseur - and the other teams using non-Mercedes engines - are eyeing an opportunity to make gains, Wolff appears unconvinced that any manufacturer other than Honda should be given scope to significantly upgrade their engine.
Speaking on April 20, Wolff said: "The principle of ADUO was to allow teams that were on the back foot in terms of the power unit to catch up, but not to leapfrog.
"And it needs to be very clear that whatever decisions are being made, whichever team is granted ADUO, that any such decision may have a big impact on the performance picture and on the championship, if not done with absolute precision and clarity and transparency.
"It needs to be clear that gamesmanship hasn't got any place here, but it needs to be with the right spirit here that the FIA acts upon an ADUO.
"The teams will have their performance pictures and, as it seems for me, there's one engine manufacturer that has a problem and we need to help. And then all the others are pretty much in the same ballpark.
"I would be very surprised, actually, and disappointed if ADUO decisions that were done would come up with any interferences into the competitive pecking order as it stands at the moment."
While Wolff speaks of gamesmanship, he could potentially be referring to the possibility of teams attempting to display lower ICE performance to ensure a better outcome when it comes to ADUO.
As the season develops, ADUO appears likely to be a topic that keeps coming up.
Watch every race weekend of the 2026 Formula 1 season, live on Sky Sports F1. Stream Sky Sports with NOW - no contract, cancel anytime
