ADUO explained: how F1’s new engine balancing system works

The opening three races of the 2026 season have confirmed the clear superiority of the Mercedes power unit, something that had already been evident during testing. Widely tipped as the benchmark even last year, the German manufacturer arrived fully prepared for the major regulation shift.

As a result, the Brackley-based team has swept up everything on offer across Melbourne, Shanghai and Suzuka, fully aware that its current engine advantage may soon begin to shrink - precisely because of the system mentioned above.

From this year, in fact, the FIA has introduced the ADUO system, short for Additional Development and Upgrade Opportunities. In essence, it allows manufacturers that are struggling more on the engine side to run their power units on the dyno for longer than the reference benchmark - in this case Mercedes - and to introduce extra upgrades depending on the performance gap.

Put simply, ADUO can be seen as a modern form of Balance of Performance, although with a key difference: it is the chasing teams that must close the gap themselves, rather than the leading outfit being slowed down, as happens for example in the WEC.

The framework behind the system is reviewed at regular intervals, with the FIA carrying out performance checks on the power units every six races.

The goal is to give manufacturers who are trailing a chance to close the gap during the season itself, rather than being forced to wait until the following year - ultimately raising the level of competition across the grid.

The extent to which engine suppliers can develop their power units depends on clearly defined performance brackets. If a manufacturer is operating between 2% and 4% below the benchmark, it is granted the opportunity to introduce one additional upgrade.

Should the deficit exceed the 4% threshold, the allowance increases to two extra upgrades. This scenario could realistically apply to Honda, which has so far appeared well adrift of the leading manufacturers.

As previously mentioned, the ADUO process is structured around a series of evaluation points, with the first major comparison taking place after six rounds of the championship.

It serves as an initial benchmark to determine whether any adjustments may be required. However, the FIA is now considering bringing that assessment forward, aiming to provide greater flexibility for manufacturers. As previously reported by GPblog, discussions around a revised timeline have already taken place.

The need for a change stems from the altered calendar, following the cancellation of both the Bahrain and Saudi Arabian Grands Prix. As a result, the six-race mark would now only be reached after Monaco, rather than Miami as originally planned.

That leaves Mercedes’ position unclear. The key question is whether Wolff and the team will attempt to block the earlier introduction of the ADUO assessment, or whether they are willing to accept the change. For the time being, GPblog understands that the Brackley-based outfit has not taken a firm stance either way.