The most powerful internal combustion engine at the start of the 2026 season belongs to the F1 debutant manufacturer Red Bull Ford. The FIA measurement results are surprising and, if confirmed, will have a very significant impact on the development of power units in the coming year and on manufacturers’ strategies.
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At the time of publication of this article, the FIA has still not published the official results of the internal combustion engine performance measurement. Teams and engine manufacturers received the results in the form of a one-page summary on the day of the Monaco GP race. According to information from several journalists, the FIA was supposed to make these results public the next day, but did not. The reason is Red Bull, which disagrees with the measurement results. According to Motorsport.com, Red Bull has requested a recalculation. The FIA is currently dealing with this, and the process is expected to take 7-10 days. The official announcement will therefore appear no later than a few days after the Spanish GP. If the FIA were to provide different results after recalculation, it would reflect very poorly on their technical experts. I wrote the rest of the article assuming these data are official; if the FIA provides changed data in a few days, I will introduce updates.
What is ADUO and how is F1 engine performance measured?
ADUO (Additional Development and Upgrade Opportunities) is a system described in detail in the FIA regulations, aimed at helping manufacturers whose engines are the weakest. Under this system, they receive additional development opportunities to balance the playing field. Each season, the FIA will measure the performance of internal combustion engines (only internal combustion) and grant benefits based on the results obtained. In 2026, the first measurement was after the Canadian GP in mid-May, and subsequent ones will be after the Hungarian GP at the end of July and after the Mexican GP at the turn of October and November. In subsequent years, this will be examined every six race weekends. A given manufacturer can qualify for ADUO once a year. So, if someone received benefits during the first measurement for this reason, they will have them until the end of the year. If they still lag in performance during the second measurement, it no longer matters.
In the case of ADUO, only the performance of the internal combustion engine is measured. The FIA performs measurements based on track data and calculates them in a complex way, taking many factors into account. Engine manufacturers agreed to such a measurement; they did not want an even more complex one that would also consider electrical components.
In the case of ADUO measurement, two levels are most important: a performance loss between 2% and 4%, and a performance loss of over 4%. This is when the most significant benefits appear. Under ADUO, manufacturers get the opportunity to improve power unit components in the current and future seasons. This refers to components that are frozen according to the regulations, meaning they cannot be changed without ADUO. Additionally, manufacturers get the opportunity to increase their budget and use additional testing hours on dynos in factories. Everything is described in detail in the regulations; a whole scale has been developed. I refer you to my very comprehensive article titled ADUO – principles of the F1 engine performance equalization system, where everything is explained in detail.
F1 Internal Combustion Engine Performance Ranking after Five Weekends of the 2026 Season
According to media reports, the FIA provided the following power ranking among internal combustion engines after the measurement covering the first five race weekends of the 2026 season. The FIA did not disclose exact values.
1. Red Bull Ford
2. Mercedes – loss between 2% and 4%
3. Audi, Ferrari and Honda – loss above 4%
A loss of 2% to 4% allows for one improvement this year and one in 2027. A loss above 4% allows for two improvements this year and two in 2027. Each power unit consists of 84 different components. The development of some of them is frozen. Therefore, changing one or two elements is not a revolution, but it will improve performance to some extent.
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We do not know the exact power values, nor the exact losses of Audi, Ferrari, and Honda. Many indications suggest that these three manufacturers are losing significantly more than 4%; it is highly probable that they have over 6% loss to Red Bull, and Honda probably even over 8%.
In May, it was estimated in the media that Mercedes’ most powerful internal combustion engine had 585 horsepower. Now we know that Red Bull has even more power. Assuming the Red Bull Ford internal combustion engine has 600 horsepower, a 1% difference is 6 horsepower. Mercedes, therefore, might have around 585 horsepower. Other manufacturers must have below 576 horsepower. According to estimates from previous weeks, Ferrari was expected to lose 20-30 horsepower to Mercedes, and Honda even around 50. This would mean that Honda’s weakest engine might have 535 horsepower, which is over 10% less than Red Bull Ford. This would align with the May regulatory changes when a new threshold above 10% loss was introduced for ADUO.
Let’s remember that current power units are complex and have many parameters. Red Bull Ford may have the most powerful internal combustion engine, but that doesn’t mean their entire power unit is the best. Many other important factors play a role. During media meetings before the Barcelona-Catalonia GP, James Vowles from Williams said that Mercedes’ engine indeed lags slightly behind Red Bull in terms of the internal combustion engine, but it has the best electrical system. The fact that a completely new manufacturer has prepared the most powerful internal combustion engine deserves emphasis. This is a great success for Red Bull.
Development Strategy of Mercedes and Other Manufacturers
Manufacturers who receive benefits under ADUO will gain greater development opportunities thanks to a higher budget cap and more hours of work on test benches in the factory. These are things that all four will gladly take advantage of from the very beginning. Audi, Ferrari, and Honda have no time to wait, and if they develop improvements worth introducing on track, they will want to implement them as soon as possible. According to unofficial reports, Ferrari may introduce improvements already for the Austrian GP, and a second set just after the summer break. Honda is reportedly preparing theirs for the Hungarian GP, but they might be delayed until just after the holidays. These manufacturers have significant losses; even if they improve their engines, it will not affect the balance of power and subsequent ADUO measurements. Mercedes’ situation is different.
Mercedes is winning everything at the start of this year without having the best internal combustion engine. This manufacturer will likely approach its development plans strategically. If they soon improved their engine and, during the next ADUO measurement, it turned out that they had overtaken Red Bull, which would additionally be more than 2% behind, then Red Bull would also receive its own ADUO benefits this year. From Mercedes’ perspective, this is a bad scenario because they would strengthen their rival. Mercedes therefore has two logical options they can use. If their planned improvements are small and do not cause them to overtake Red Bull, they can introduce them whenever they want. If they devise improvements that would allow them to overtake Red Bull, they can wait to introduce them until after the Mexican GP. If they did so and then overtook Red Bull’s engine, Red Bull would only receive approval for its own ADUO improvements around May 2027.
ADUO and engine changes for the 2027 and 2028 seasons
There is one big unknown regarding ADUO. The F1 Commission has approved changes to the power units for the 2027 and 2028 seasons. According to current F1 regulations, manufacturers can modify their engines if the regulations change. We do not yet know the specific provisions that have been changed for the next two years (there is only a general announcement), but this will have a very significant impact on ADUO. Some engine components that are supposed to be frozen in development for the coming years will likely be unfrozen due to regulatory changes, and everyone will be able to modify them. This means that the benefits of ADUO will be limited. However, there is a second, more important issue. ADUO increases the budget cap and provides broader testing opportunities. Manufacturers who have qualified will be able to work longer on engines for the 2027 season, which will give them an advantage. I am sure that Red Bull and partly Mercedes will protest. This may lead to changes in the ADUO system.
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