The FIA has explained why Formula 1’s engine catch-up system cannot show every part of power unit performance. The system measures the internal combustion engine, while the complete package also includes electrical energy recovery.
The governing body accepts that this creates a limited picture. It still believes the current calculation gives a consistent base for granting extra development work.
The system compares combustion performance
The abbreviation ADUO means Additional Development and Upgrade Opportunities. It was introduced with the 2026 power unit rules to prevent a large early gap from lasting for several seasons. The calculation uses information collected while the cars are running. Engine speed, input shaft torque and electrical deployment help the FIA isolate the work completed by the combustion engine.
Circuit layout also affects the value of engine power. The method therefore applies a weighting for the influence of power on lap time across the measured laps. Each manufacturer receives a position in the performance index. Extra opportunities begin when an engine falls at least two percent behind the leading unit.
Two percent opens the first allowance
An engine between two and four percent behind receives one extra homologation upgrade. The allowance applies in the current season and provides another opportunity in the following year. A larger deficit gives an engine manufacturer more development freedom. The regulations also connect each band to extra dynamometer hours and additional room under the power unit cost limit. These measures do not guarantee a performance gain. A manufacturer still has to design, validate and produce a part that works reliably in the car.
The fixed bands give every company the same published threshold. They also make small differences near a boundary important for future development work.
The main weakness comes from the division inside the power unit. The performance index focuses on the combustion engine instead of measuring the full hybrid package. Electrical deployment can change straight-line speed and lap time. Battery condition, control software and energy recovery also affect how long a driver can use maximum power. A car may have a strong complete package even when its combustion engine sits below the benchmark. Another car can show the opposite balance between combustion and electrical performance. The FIA has not described the index as a complete ranking of every power unit. It is a defined calculation for deciding which manufacturers receive the published allowances.
The permitted work reaches beyond one component
Another debate concerns the parts that become available after a manufacturer qualifies. The initial comparison concerns combustion performance, but some permitted changes can affect the wider power unit. Teams have questioned whether that connection can reward a package that is already competitive. The concern became stronger after the first 2026 assessment produced an unexpected order.
The FIA checked the submitted data again after manufacturers raised questions. The review did not replace the measurement with a subjective estimate of complete car performance. A subjective ranking would create a different problem. Chassis efficiency, cooling choices and gear ratios can hide or increase the apparent effect of the same engine.
Manufacturers supported a narrow calculation
Earlier discussions included broader ways to measure performance. Engine suppliers preferred a calculation that could be repeated from recorded data without judging each car as a whole. That choice kept the index focused on the V6 combustion unit.
It also reduced the number of assumptions required when comparing cars with different aerodynamic drag.
The first months of the new rules have exposed the compromise. A narrow test is easier to repeat, but it cannot describe every source of total power unit performance. The FIA has scheduled later assessment periods under the same regulations. Any procedural change requires published timing because development budgets depend on the result.
The next review will use more race data
Later assessment periods will contain information from more circuits and conditions. A wider sample reduces the influence of one unusual weekend or one energy-heavy layout. Engine reliability is measured separately from the performance index. An engine can produce a competitive figure while losing race mileage through failures or component changes. Championship results also include the chassis, drivers and race operation. ADUO does not attempt to convert those factors into an engine ranking. The present system remains in force after the FIA’s explanation. Its limits are now stated more clearly as the second half of the season approaches. The first ADUO review used data from the opening six Grands Prix. FIA technicians collected information from every manufacturer under the same procedure. They then compared the calculated combustion output with the leading engine. A deficit below two percent produced no extra upgrade. A gap between two and four percent created one additional opportunity. A deficit above four percent opened two extra opportunities. This sliding scale gives the weakest engine more work without removing homologation. The next assessment can also reduce an allowance if the measured gap closes. Manufacturers therefore receive help only while the recorded deficit remains large enough.
Homologation normally fixes the main specification for a defined period. Changes remain possible for reliability, safety and cost reasons after technical approval. ADUO adds a performance route that uses fixed thresholds instead of a general request. A qualifying manufacturer can introduce another approved specification during the season.
It can also carry part of that work into the following development cycle. Every change still passes the normal legality checks before appearing at a race. The allowance does not permit unlimited testing or unlimited spending. Wind-tunnel restrictions and the financial regulations continue to apply across the whole team. The electrical omission matters because the 2026 formula increased hybrid power. A strong battery, control system and motor can hide weakness in combustion output. The opposite combination can make a sound engine look slow on the circuit. Chassis drag and cooling choices also affect the speed recorded on a straight. The index avoids those variables by using a narrower calculation. That makes the comparison repeatable, but it cannot describe the complete car. FIA officials have openly described this technical limitation. They regard ADUO as a controlled catch-up tool rather than a complete ranking of power units. Teams will continue gathering normal race data before the next review. Different circuits place different demands on fuel use and electrical deployment. Several samples are needed before one unusual track loses its influence. The system also protects confidential engine information from public disclosure. Supporters may learn which allowance applies without seeing every internal measurement. Manufacturers can then plan upgrades around the published development windows. The sporting result still depends on chassis performance, reliability and race execution. ADUO changes the available engineering work, but it never awards championship points directly. The FIA compares manufacturers after six events rather than one weekend. That period reduces the effect of a circuit that unusually suits one engine. The calculation also uses the best result from each supplier. A slower customer car does not automatically create an upgrade right. The system measures a power-unit deficit, not a team’s finishing position. An approved opportunity also keeps the normal budget, testing and legality rules. A manufacturer must design, validate and introduce every change through the established process.
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