McLaren believes closer collaboration with Mercedes High Performance Powertrains has played an important role in its 2026 Formula 1 performance step, with Andrea Stella identifying power unit optimisation as the area offering the greatest remaining potential. Work with the Mercedes HPP engineers on hybrid-system mapping has helped resolve some of the power-delivery difficulties experienced earlier in the season, although McLaren still believes there is more performance to unlock alongside its recent aerodynamic progress.
The improvement has become increasingly visible in recent races, culminating in McLaren’s breakthrough in Budapest. The MCL40’s progress was not the product of a single modification, however. It followed months of work across several areas of the car, combining McLaren’s wider development programme behind the Hungary breakthrough with a much deeper understanding of how to exploit the Mercedes power unit.
Andrea Stella sees more potential in the Mercedes power unit
Andrea Stella recently reflected on McLaren’s work during the first half of the season. The team principal highlighted how the April break, created by the cancellation of the two scheduled Middle Eastern races, provided an opportunity to understand the MCL40 in greater depth and identify the specific areas on which development needed to concentrate.
The Hungarian Grand Prix was the result of much of that work, but the rate of development remains the key parameter for McLaren. Continuing to understand the car quickly enough to introduce the right modifications will be crucial if the British team is to maintain its progress through the second half of the championship.
When asked where McLaren still sees the greatest opportunity to find performance, Andrea Stella had little doubt: the power unit.
“There is still a lot of room for improvement, particularly regarding the power unit. We are working very well with our partners at HPP (Mercedes), including the interaction between the driver and the power unit itself.”
Those comments indicate how much the relationship between McLaren and Mercedes HPP has evolved since the opening phase of the championship. Early difficulties in understanding and tailoring the delivery characteristics have gradually been addressed through closer cooperation between the Woking team and Mercedes’ powertrain operation at Brixworth.
Why hybrid power unit mapping is so important in F1 2026
Extracting the maximum from the power unit has become one of the central technical challenges of the current generation of Formula 1 cars. Both energy recovery and electrical deployment need to be carefully controlled, meaning the harvesting and deployment phases must be mapped in extremely fine detail.
That requires a precise energy strategy throughout an entire lap, with the configuration adapted to the characteristics of each circuit. A solution that works at one track may not necessarily be optimal somewhere with a very different mix of braking zones, acceleration phases and straights.
Because the power units and their operating parameters remain tightly controlled, Mercedes HPP engineers carry out the changes requested by customer teams such as McLaren. That makes close cooperation essential: McLaren must identify exactly what it wants from the system, while the Mercedes specialists must translate those requirements into appropriate power unit settings.
The process often begins with driver feedback. A driver may identify a specific point on the lap where the delivery is not behaving as desired. When the throttle is applied, for example, the torque delivery may be too aggressive. That can create wheelspin, reducing traction while also overheating the tyre surface.
Problems can also occur under braking, when the power unit is recovering electrical energy. The balance between energy harvesting, braking behaviour and subsequent deployment therefore has a direct influence on how naturally the car responds to the driver’s inputs.
McLaren works to reduce energy clipping on the straights
Once a driver identifies a problem, the feedback is passed to the race engineer, who can isolate the relevant part of the lap and analyse the data. One of the other areas requiring careful management is excessive clipping, when electrical deployment is reduced before the end of a straight.
Energy therefore has to be rationed carefully across the lap so that it is deployed at the moments when it delivers the greatest benefit. The objective is to avoid spending too much electrical energy too early and then suffering a more significant reduction in power later on a straight.
This is one reason why the same Mercedes power unit cannot simply be operated identically in every chassis. McLaren and Mercedes have different vehicle dynamics, including suspension stiffness and suspension kinematics, so a setting that works well for the works Mercedes car may not be ideal for the MCL40.
That distinction helps explain some of McLaren’s early-season difficulties. The team had to learn how to integrate the new power unit characteristics with its own chassis rather than simply copying solutions developed around the Mercedes W17.
Mercedes HPP helped McLaren make its 2026 step forward
Andrea Stella requested a number of changes from Mercedes HPP during the opening part of the championship, and the Brixworth engineers progressively implemented them within the limits permitted by the regulations. The reliability and integrity of the power unit cannot be compromised simply to satisfy a customer team’s performance request, so the process requires gradual refinement.
Mercedes HPP has also provided McLaren with extensive guidance on how to use the 2026 power unit more effectively. That high-level technical support has helped the Woking team refine its hybrid-system mapping and better integrate energy deployment with the behaviour of the MCL40.
The progress has occurred alongside McLaren’s aerodynamic development. Mercedes itself was surprised by the scale of the MCL40 upgrade package introduced in Hungary, while the team has since stressed that it does not regard the Budapest success as the end of the development process. Andrea Stella has instead played down suggestions that Hungary represented a definitive turning point.
McLaren’s chassis concept adds another layer to that challenge. The team’s decision-making around the MCL40 included a distinctive approach to its dimensions and vehicle architecture, with the short-wheelbase philosophy influencing the car’s development path.
That is why the recent improvement cannot be attributed exclusively to either aerodynamics or the Mercedes engine. McLaren has been working to make the individual elements operate more effectively as a complete package, with power delivery, energy management, mechanical behaviour and aerodynamic performance all interacting with one another.
The aerodynamic side of the MCL40 is also expected to continue evolving. McLaren has tended to introduce larger development packages than some rivals, a contrast also evident in Ferrari and McLaren’s different approaches to the 2026 upgrade race.
For McLaren, however, Andrea Stella’s assessment makes the next priority clear. Even after the team’s major aerodynamic work and its step forward in Hungary, there is still significant potential to extract from the Mercedes power unit. The increasingly close interaction between McLaren and the HPP engineers at Brixworth has already contributed to the MCL40’s improvement, and further refinement of the hybrid system could help reveal more of the performance created by the team’s recent aerodynamic developments.
