The second F1 ADUO review will reach its decisive cut-off point at the 2026 Hungarian Grand Prix, shortly after Toto Wolff publicly described Mercedes as having the most powerful power unit on the grid. Laurent Mekies agrees with the Mercedes team principal’s assessment, although the Red Bull boss responded with understandable frustration following the surprising outcome of the FIA’s first evaluation period.
The Hungarian Grand Prix, which takes place this weekend at the Hungaroring in Budapest, will be important for more than simply bringing the first half of the 2026 Formula 1 season to an end before the summer break. The 11th round of the campaign will also represent a significant watershed for the ADUO system and the power unit development opportunities available to Formula 1’s manufacturers.
What the F1 ADUO review means for power unit manufacturers
ADUO is the system devised by the FIA to allow power unit manufacturers suffering from a performance deficit to work on their respective engines and reduce the gap to Formula 1’s benchmark V6. It therefore has the potential to influence the competitive balance between Ferrari, Mercedes, Red Bull Ford and the other manufacturers as the new regulatory cycle develops.
The first event used to define this particular assessment window was the Canadian Grand Prix. That decision was taken to permit more realistic measurements following the cancellation of two Middle Eastern events because of the conflict between Iran and the United States. Six races will have taken place between the Canadian and Hungarian Grands Prix, completing the intended interval for the second round of measurements.
The Hungarian weekend consequently carries additional technical significance beyond the immediate championship battle. Fans following the event can find the complete 2026 Hungarian Grand Prix timetable and broadcast information ahead of Formula 1’s final round before the summer shutdown.
The new ADUO data should be released within two weeks of the Hungarian Grand Prix. However, what happened after the first evaluation period suggests that this should not be treated as a certainty. The figures covering the opening quarter of the season have still not been made public. Only the power unit manufacturers were informed about the extent to which they could work on their engines and the resources they were permitted to commit.
Mercedes received an allowance despite winning eight races
Following the Canadian Grand Prix, the Red Bull Ford engine was reportedly judged to be the strongest-performing power unit. The result was surprising because it meant Mercedes was granted an ADUO allowance, believed to permit the recovery of a performance deficit of between two and four per cent.
However, the power unit produced at Mercedes’ Brixworth facility has powered the winning car in eight of the ten Grands Prix held so far. The apparent contrast between its results on the track and the outcome of the first ADUO assessment was therefore greeted with surprise by many Formula 1 insiders.
The situation has also attracted attention because Mercedes-powered cars have recently encountered complicated energy deployment problems. Further context on those difficulties can be found in the analysis of George Russell’s qualifying battery problems, which became particularly visible during the Belgian Grand Prix weekend.
Toto Wolff calls Mercedes the most powerful F1 power unit
Toto Wolff’s comments after the Belgian Grand Prix did not go unnoticed. While discussing the power problems experienced by Mercedes engines on the straights at Spa-Francorchamps, the Mercedes team principal appeared to acknowledge that the German manufacturer possesses Formula 1’s most powerful hybrid power unit.
“We had a problem that affected all the Mercedes engines: there was a lack of power on the straight, and that penalised him enormously. The responsibility is 100 per cent ours. As a team, we are giving everything: we have the most powerful power unit, a car capable of winning, and everyone is doing their best to minimise mistakes. But mistakes happen because we are human beings,” Toto Wolff said.
“I am proud to be part of the HPP and MGP organisation. They are groups of people who give everything they have. This year, we have produced a genuinely very strong product, and I would rather have to solve reliability problems than try to make a slow engine or car fast.”
Mercedes’ difficulties on the Spa-Francorchamps straights arrived during a weekend in which Ferrari once again demonstrated encouraging competitiveness. Although Ferrari ultimately missed out on victory, the team left Belgium with reasons for optimism, as the wider analysis of Ferrari’s performance on the hard tyres at Spa explains.
Laurent Mekies agrees with Toto Wolff’s Mercedes verdict
Laurent Mekies did not miss the opportunity to highlight Toto Wolff’s admission. After the disappointment surrounding the ADUO measurements from the first quarter of the season, the Red Bull team principal drew attention to his rival’s comments and openly agreed with the assessment.
“Toto is right. I also think they have the most powerful power unit,” Laurent Mekies said after the Belgian Grand Prix. “And they certainly had a significant advantage on the straights this weekend.”
“But it is not the first time. They have an advantage on the straights during most weekends. It was even more evident this weekend because of the circuit characteristics. So, we will see what happens. As you said, the second period will conclude in Budapest in one week. We will see what happens.”
That verdict gives the approaching FIA assessment an especially intriguing dimension. Red Bull believes Mercedes regularly possesses a straight-line advantage, while Toto Wolff himself has described the Mercedes unit as the most powerful. Nevertheless, Mercedes benefited from the first ADUO calculation after the Red Bull Ford power unit was reportedly established as the initial reference.
Could the second ADUO evaluation reverse the order?
Once the Hungarian Grand Prix is complete, Formula 1 will enter its summer break, but attention will quickly shift towards the results of the second ADUO measurement period. The performance figures recorded by the Red Bull Ford and Mercedes power units were already understood to be close during the opening months of the season, meaning their positions could potentially be reversed following the latest assessment.
The Hungaroring itself presents a very different technical challenge from Spa-Francorchamps. Its greater emphasis on low- and medium-speed corners could alter how the relative strengths of the cars and power units are perceived. Ferrari also believes the circuit may be somewhat more favourable to the SF-26, although the team has issued a warning against excessive optimism before the Hungarian GP.
Even if Mercedes is designated as Formula 1’s new power reference, Red Bull may still be denied an ADUO development opportunity. If the Red Bull Ford power unit is assessed as being less than two per cent behind the Mercedes benchmark, it would remain inside the threshold and would not qualify for an additional allowance.
The second F1 ADUO review could therefore confirm one of several outcomes: Mercedes may replace Red Bull Ford as the reference power unit, another manufacturer may receive additional development freedom, or Red Bull may remain close enough to the benchmark to receive no opportunity to upgrade despite believing Mercedes holds a clear advantage.
Whatever the precise result, the assessment following Budapest will be closely watched throughout the paddock. Toto Wolff and Laurent Mekies already agree on which manufacturer possesses the strongest power unit. The remaining question is whether the FIA’s measurements will reach the same conclusion and what that verdict will mean for the development battle during the second half of the 2026 Formula 1 season.
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