Mercedes will not introduce its ADUO Power Unit upgrade at the Italian Grand Prix, despite fitting Andrea Kimi Antonelli with a completely new engine at Monza. The Formula 1 championship leader has reached the 2026 regulatory limit of four internal combustion engines and will therefore start from the back of the grid, while Mercedes’ upgraded ADUO specification is instead expected to debut in October at either Austin or Mexico City.
The grid penalty facing Andrea Kimi Antonelli has become one of the major talking points ahead of the Italian Grand Prix. Mercedes has decided to introduce a fifth Power Unit on the Italian’s W17, primarily to rebuild an engine pool that has been reduced by previous failures rather than to provide an immediate performance increase.
Kimi Antonelli takes fifth Mercedes engine at Monza
Andrea Kimi Antonelli has now reached the Power Unit allocation permitted under the 2026 regulations, having already used four ICEs. Mercedes will consequently install an entirely new unit this weekend, a decision that means the championship leader must start his home Grand Prix from the back of the grid.
The new engine will be Andrea Kimi Antonelli’s fifth of the season. As GP-News has already detailed, the fresh Mercedes Power Unit at Monza is focused on reliability rather than additional performance.
Everything suggests this will not be Andrea Kimi Antonelli’s final penalty of the season. Including Monza, ten rounds would remain on the 2026 calendar when taking into account the expected cancellation of Qatar and Abu Dhabi, which is due to be officially confirmed, and the addition of Imola.
Teams are therefore calculating how much mileage remains to be completed and assessing which circuits make a grid penalty less damaging. Mercedes has selected Monza for Andrea Kimi Antonelli, probably the circuit on the entire calendar where recovering positions is easiest.
Mercedes ADUO engine upgrade planned for October
The fifth Power Unit that Andrea Kimi Antonelli will use at Monza will not contain the upgrades permitted under ADUO. Mercedes has earned the opportunity to introduce an updated Power Unit, but its debut is planned for the American leg of the season in October, either at Austin or, alternatively, Mexico City.
That means Andrea Kimi Antonelli and George Russell are expected to use six Power Units each in order to complete the full championship.
Mercedes sits within the group of manufacturers entitled to additional development under the FIA’s ADUO regulations. The system provides extra development opportunities depending on the measured performance deficit of each manufacturer’s internal combustion engine, with Mercedes currently falling within the FIA’s 2-4% deficit band.
Why Mercedes chose Monza for Andrea Kimi Antonelli’s penalty
The main reason Mercedes decided to fit a new Power Unit to Andrea Kimi Antonelli’s car at the Italian Grand Prix is the condition of his engine “pool”, the term used for the collection of components still available to a driver.
In Andrea Kimi Antonelli’s case, some failures involving previous Power Units were terminal, leaving no possibility of recovering the affected components. That reduced the number of usable parts available to Mercedes and created the need to introduce another complete unit.
The timing is particularly important with the next four rounds in mind, three of which will take place on street circuits. Baku would still offer opportunities to recover positions after a grid penalty, but starting from the final row in Madrid or Singapore would almost completely compromise the chances of scoring a strong haul of points.
Monza therefore allows Andrea Kimi Antonelli to take the penalty without completely eliminating his chances of achieving a good result, while at the same time significantly improving the condition of his Power Unit pool for the remainder of the season.
George Russell has a healthier Mercedes Power Unit pool
George Russell’s situation is slightly better. Although he has currently used the same number of components as Andrea Kimi Antonelli, George Russell has already homologated a fourth turbocharger, one more than his Mercedes team-mate.
Even so, George Russell has a larger pool of usable components available because he has suffered fewer terminal failures than Andrea Kimi Antonelli. That gives Mercedes slightly more flexibility in managing the Briton’s Power Unit allocation as the season progresses.
Mercedes is therefore using Monza primarily to restore Andrea Kimi Antonelli’s available engine pool before the championship enters a sequence of circuits where taking a penalty would be significantly more costly. The genuine performance step is being held back for October, when the new ADUO specification is scheduled to arrive at either Austin or Mexico City.
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