Zak Brown says Mercedes haven't provided McLaren with their latest power unit spec

The reigning F1 Constructors' Champions have endured a frustrating start to the 2026 season struggling with performance while also suffering from power unit-related reliability problems.

McLaren head into the British Grand Prix third in the F1 Constructors' Championship, with Mercedes dominating the campaign by winning seven of the opening eight races, while Ferrari claimed the other victory through Lewis Hamilton at the 2026 Barcelona-Catalunya Grand Prix.

Speaking at Silverstone on Friday, Brown insisted McLaren's fortunes would improve as upgrades arrive over the coming races.

"We have some work to do. We'll catch up," he said. "I think we'll be winning races this year, so I'm quite optimistic for the future."

Mercedes have also claimed pole position at every race so far this season, underlining the advantage currently enjoyed by the Brackley-based squad.

Brown, however, believes the competitive picture will soon become far more balanced, predicting McLaren and Red Bull Racing will both reach the top step of the podium before the season ends.

Brown identified one key factor behind McLaren's current deficit, explaining that his team is the only Mercedes-powered operation yet to receive the latest specification power unit.

"We just need to get some more development on the car, we need to get the current Mercedes engine," he explained. "We're the only ones without the new engine, that will be coming to us shortly."

The American admitted it has been frustrating knowing extra performance is available but not yet fitted to McLaren's cars.

"Any time you have performance that you know is coming but you don't have it on your car, you want to get it as quickly as possible," Brown said.

He stressed the delay is not due to supply issues but simply timing, with McLaren working through its planned engine allocation for the season.

Brown explained that other Mercedes customers received the latest specification earlier because circumstances forced their hand, pointing to Carlos Sainz requiring an engine change at Williams Racing, while other teams had different deployment schedules.

"You want it as quickly as you can but you need to run the cycles through the engines," Brown said. "Obviously you can move things in and out, but we will want to see them hopefully next race."

If the upgraded Mercedes power unit arrives as expected for the Belgian Grand Prix, Brown believes it will coincide with further development work aimed at improving the MCL40's overall performance.

McLaren, who won both world championships last season as a Mercedes customer team, are also focused on making the car easier for Norris and Piastri to extract consistent pace from while improving overall power unit optimisation.

Brown expects the next two European races to provide a clearer indication that McLaren are moving back towards the front of the field.

With Mercedes-powered teams including the factory squad, Williams Racing, Alpine F1 Team and McLaren all sharing the same engine family, the Woking outfit hopes finally receiving the latest specification unit will help unlock the performance needed to challenge Mercedes and Ferrari more consistently in the second half of the season. (Reporting by Agnes Carlier)