F1 rated Red Bull's engine the benchmark on Sunday, then agreed to shrink its advantage by Wednesday.
On Monaco race day, a one-page note from the FIA's Geneva office reached every Formula 1 engine manufacturer. Titled "Confirmation by FIA to Power Unit Manufacturers of ADUO status," The Race reports, it contained a three-line verdict: Red Bull Powertrains is the benchmark, Mercedes is entitled to one upgrade homologation, and Ferrari, Audi and Honda are entitled to two each.
The verdict
Mercedes has won all six grands prix this season, as Sky Sports noted in its report on the ruling, and the team supplying the championship-winning power unit has now been judged more than 2 percent adrift of the best engine in the field. Max Verstappen, seventh in the drivers' standings, carries the unit the FIA rated above all others. The explanation for the inversion is in the measurement: the Additional Development and Upgrade Opportunities assessment scores the internal combustion engine alone, excluding harvesting, deployment and battery efficiency, the systems that have decided lap time all season.
Under the mechanism first detailed by The Race, a manufacturer judged more than 2 percent behind the benchmark ICE receives one upgrade homologation this season and another for 2027, plus an additional $3m of cost cap allowance and 70 extra bench hours. Past 4 percent the entitlement doubles to two homologations per year, on a sliding scale of money and dyno time that could be worth $19m to Honda if its deficit exceeds 10 percent. The Geneva note gave each manufacturer its category and nothing else; the FIA withheld the percentages themselves, understood to be for intellectual property reasons.
Laurent Mekies had argued the opposite ranking weeks earlier. "What we see is certainly Mercedes, a long way ahead of most of us," the Red Bull team principal said at the team's factory, estimating his package three tenths adrift, per The Race. Toto Wolff had already objected to rivals treating the mechanism as a ladder: "The principle of the ADUO was to allow teams that were on the back foot to catch up, but not to leapfrog." Both men got a result they did not ask for. Red Bull is barred from upgrading the engine its rivals are now funded to chase, and Mercedes can bank its homologation, develop on the bench, and deploy only when it chooses, which keeps the benchmark frozen exactly where it is. Red Bull has since pushed the FIA for clarity on the findings, and GPFans reports the governing body has agreed to re-examine its data from the opening five races.
The repeal
Three days after the Geneva note, Formula 1 announced that the FIA, FOM, the teams and the manufacturers had agreed a staged rebalance of the very formula the verdict had just scored. ICE power rises from 400kW to 420kW in 2027 and 450kW in 2028, with fuel energy flow up 5 percent and then 13 percent. MGU-K deployment in races drops from 350kW to 300kW, with Overtake Mode retaining the full 350. Harvesting capacity climbs to 375kW and then 400kW. The notional split between combustion and electric power moves from 53/47 to 58/42 next year and 60/40 the year after. Everything awaits a World Motor Sport Council vote on June 23 in Macau.
That package is the compromise of two proposals The Race described as deadlocked before the verdict landed: a full 50kW lift in 2027 requiring new hardware, which Audi and Ferrari resisted, against a 20kW step on current hardware first. The agreed schedule is the staged version, and it arrived inside 72 hours of the ADUO note. Ferrari had opposed loosening the rules while it believed Mercedes was the benchmark and would therefore be frozen by ADUO, The Race reported; once the verdict freed Mercedes to upgrade anyway, that calculation lost its premise.
What the two documents do to each other
ADUO scores the combustion engine, and the rebalance raises that engine's share of total power to 60 percent by 2028. The component the FIA graded is the component about to appreciate, which makes the verdict matter more over time, not less. A benchmark rating that looks academic in a season decided by energy management becomes the asset to hold in a formula returning to combustion, and Red Bull holds it while locked out of developing it.
Clipping on long straights, the deployment shortfall PN has tracked since Canada, is precisely what the rebalance is engineered to remove: less electric deployment to sustain, more harvesting to refill the battery, more combustion power underneath. The FIA's single-seater director Nikolas Tombazis told manufacturers earlier this year he was "personally quite open to the idea of complicating the parameters a bit," per The Race; the manufacturers declined the more complex measure when it was offered. Having now seen what the simple one produces, several may want that conversation back.
Macau on June 23 settles the formal question, and the FIA's review of its first-five-races data settles the nearer one. If the audit moves any manufacturer across the 2 or 4 percent lines, the upgrade map redraws itself before the summer. If it stands, the 2026 season continues as a development race running in reverse: four manufacturers tuning engines to catch a benchmark whose own makers insist it is not the best, in a formula whose replacement schedule everyone has already signed.