Andrea Stella addresses Mercedes trust concerns amid McLaren engine frustrations

Andrea Stella has opened up on why he believes McLaren currently has an engine performance deficit to Mercedes, despite sharing a common supply.

Both the Mercedes and McLaren teams receive their power units from Mercedes High-Performance Powertrains [HPP], the power unit department that integrates with the factory team.

Andrea Stella rejects Mercedes trust concerns

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Reigning world champion team McLaren is having a quieter season in 2026, with the Woking-based squad yet to claim a victory as Lando Norris and Oscar Piastri have had to be content with a sprinkling of podium finishes.

Despite sharing an engine supply with Mercedes, which has won all bar two of the Grands Prix so far, McLaren’s competitive level simply hasn’t been as strong as that of the factory team, or Ferrari, with Andrea Stella’s squad instead battling with Red Bull most weekends to be the third-quickest team.

Most of this pace deficit, Stella has explained, is down to McLaren being behind on the development curve, having not been able to “maintain a certain gradient” throughout a phase of 2025 as the team had to worry about the onslaught of Red Bull and Max Verstappen.

With updates coming to the MCL40 in upcoming races, the upside of development is still plentiful in this relatively early stage of the regulation cycle, but some of McLaren’s deficit is also down to its understanding and ability to exploit the full potential of the Mercedes power unit.

At Silverstone, Stella explained, this was noticeable at a circuit that is energy-starved, as he pointed out the areas in which McLaren is lagging.

“Power unit exploitation and power unit performance are particularly important, and I have to say, and I’ve said that other times, that we still seem to have a little bit of a deficit in extracting the most from the HPP power unit,” he told the media, including PlanetF1.com.

“I think we have three to four tenths that we have, because we are behind in terms of development of our car.

“If you look at the GPS overlays, it becomes apparent that somehow we need to keep our conversation open with HPP, because there’s some performance we seem to be leaving behind.”

Mercedes’ own exploitation of the potential of the power unit saw its drivers engaging in unusual tactics, such as releasing the accelerator on the run to the finish line in a unique deployment technique, and Stella said this was not something McLaren had been briefed on prior to the weekend.

“It kind of surprised us a little bit, because it’s not something that we discussed, and nor unsure at all that it is available to us, because it probably requires some further elements, let’s say, to use the power unit,” he said.

“There are definitely conversations ongoing with HPP at the technical level to make sure that we use what is available in this power unit, which is brilliant; it’s a really great piece of technology.

“There’s a lot of performance, which is also in the details of the exploitation, and we are now waiting to see if we can upgrade our specification, and if this helps exploitation somehow, it should be just a reliability upgrade.

“I’m not sure that’s the case, but definitely there are some other factors that we need to keep discussing with HPP, because when we look at the performance in the straights, even taking into account the fact that they may have less drag, there are still some question marks.”

McLaren has not yet been fitted with the latest-specification HPP power units, unlike the factory team or fellow customers Alpine and Williams, due to its place in the cycle on mileage and usage, but it is believed that these units are merely reliability-updated configurations, rather than introducing the ADUO upgrade that Mercedes has been recently granted.

“We understand the reasoning,” Stella said of the fact McLaren has fallen a step behind on specification.

“We trust HPP; we have had such a great collaboration in previous years. They have been totally instrumental in McLaren becoming world champion twice, so this is not changing the foundation of the relationship.

“The conversation is ongoing. They are running fast, like we are running fast to try and develop our car. They are running fast with four teams to supply, so there are some conditions whereby it was not possible to supply the power unit to McLaren. Hopefully, this is going to happen at the next event [at Spa].”

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It’s worth remembering that McLaren defeated Mercedes with its own power units to win back-to-back Constructors’ Championships in 2024 and ’25, a feat that saw Toto Wolff label McLaren the “enemy in the house”.

While there are strict regulatory provisions in terms of what engine providers are required to supply and disclose to customers in order to ensure parity, the complexity of the new regulations is such that it’s not unimaginable to think that morsels of knowledge and operational nous are being held back rather than being proactively offered in advance.

When asked if he believes HPP is being as transparent and proactive as possible with McLaren, Stella said he has no reason to doubt the team’s supplier.

“I think, when it comes to the power unit exploitation and the opportunities that we have in this area, it’s a fact that we have opportunities, but the implication is not necessarily that HPP is not trying hard enough,” he explained.

“I think HPP, they are, like for any other team in a process of development, in a process of fixing reliability issues; we have been affected by battery problems, some other teams by ICE problems.

“They are running as fast as they can, which means that it’s difficult for them to carry forward all the solutions, all the fixes; even the allocation of the power units based on the actual amount of mileage per car, because it looks like here we are not on the latest specification, because Alpine and Williams have accrued more mileage than us, and they were more in need of upgrading their engines.

“So I think it’s just the fact that everyone is working at maximum pace, and there are a few things that can be left behind, so we accept that this is part of the conversations we are having with HPP.

“I never want to miss a chance to say that we always remain in excellent relationships, but like anything in Formula 1 when you go at maximum pace, sometimes there are a few bits that we could have done better.

“I very much appreciate in my conversation with HPP that they do say, ‘Yeah, we see your point here, we could have done better’, but it’s the same thing as a team, with as many things we could have done better.

“This is not something about HPP not trying hard. It’s about everyone trying to go as fast as possible, and I think it’s quite natural that, as a customer team, you remain a bit on the back foot.”

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