Red Bull Powertrains will continue into the second half of the season as the only Formula 1 engine manufacturer that has not been granted an upgrade opportunity for its power unit.
With the arrival of new power units for 2026, the FIA introduced a catch-up mechanism for struggling manufacturers known as Additional Development and Upgrade Opportunities (ADUO).
The system measures the relative performance of all the manufacturers' internal combustion engines and hands out upgrades, increased cost cap ceilings and additional dyno time to those that have fallen behind.
Manufacturers more than 2% off the performance of the lead manufacturer are granted a single additional power unit upgrade for the current season and the following season, while those that are more than 4% behind receive two upgrades for the current season and two more for the next season.
The first round of assessment took place after the opening six races and found Red Bull had the benchmark internal combustion engine ahead of its rivals -- much to the team's surprise.
Mercedes was deemed to be more than 2% off Red Bull and was given single upgrades for 2026 and 2027, while Ferrari, Audi and Honda all received double upgrades as they were deemed to be more than 4% off.
The second assessment period took place between the Monaco and Dutch Grands Prix, with the FIA announcing on Wednesday that no further upgrade opportunities have been handed out.
"For the second period, no additional homologations were granted to any of the Power Unit Manufacturers," the FIA statement said.
"Due to the confidential nature of this information, no further details on Power Unit performance index measurements will be communicated."
Under the ADUO rules, the upgrade opportunities are not cumulative during a season, meaning Mercedes, Audi, Honda and Ferrari has not gained extra opportunities simply by remaining adrift of Red Bull.
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Although the governing body did not publish details, the fact no changes have been made means none of the rival manufacturers have improved enough in the six race period to extend its performance advantage to more than 2% over Red Bull.
The FIA has not revealed its process for assessing the performance of the internal combustion engines due to concerns manufacturers would attempt to game the system.
It's initial ruling that Red Bull had an advantage after the first six races came as a surprise, but the FIA confirmed those results in its statement on Wednesday.
Ferrari, Audi and Honda all introduced one of its power unit upgrades since the first assessment, while Mercedes has yet to use its upgrade opportunity for 2026.
FIA director of single seater operations, Nikolas Tombazis, is convinced the system is working as intended, but left the door open to evolving the ADUO mechanism in the future.
"The FIA has undertaken thorough and exhaustive analysis as part of our ADUO review process," he said. "With the release of the findings of period two, we are confident that, based on the quality of the data, its analysis is incredibly robust, giving us a high level of confidence in our findings.
"We also have to respect the confidentiality and intellectual property of the teams and their Power Unit Manufacturers in disseminating any details from the findings.
"This is the first year of ADUO so naturally there are areas which we may evolve over time, in discussion with all the PU Manufacturers"