McLaren MCL39: four technical masterpieces behind the 2025 F1 world championship. The McLaren MCL39 helped the Woking team secure its 10th Constructors’ Championship.

World championship glory

McLaren has secured its 10th Constructors’ Championship in the history of the team. At the heart of this remarkable achievement is the MCL39, a car that represents the pinnacle of engineering under the complex ground effect regulations. There is no single secret behind the success of Oscar Piastri and Lando Norris’ car; its superiority is the result of excellence in every technical area, with some elements standing out above the rest.

Wind tunnel and aerodynamic development

In Formula 1, aerodynamics dominates performance, and the McLaren MCL39 was no exception. However, the car’s strength did not come from radical floor or front wing geometries or daring bodywork lines. The difference lay in McLaren’s ability to continuously produce effective updates without compromising correlation or drivability—problems that affected many rivals struggling with the intricacies of ground effect. Andrea Stella has often emphasized the importance of focusing on fundamentals, developing skills and working methods that contributed to flawless aerodynamic development. Human capital was central to this achievement, but alone it would not have been enough to achieve such effectiveness.

Perhaps the most significant development for McLaren was the activation of their own wind tunnel in autumn 2023. While some initial benefits were seen in 2024, it was with the MCL39 that the team could fully develop the car in the new facility, yielding visible results. Among its many advantages, the larger simulation chamber minimized wall interference, enabling major improvements in slow corners with large steering angles—a long-standing weakness for McLaren. From a team once on the brink of collapse, McLaren had developed the financial strength necessary for these investments, highlighting another masterpiece orchestrated by Zak Brown: the financial strategy behind their success.

Chassis architecture and packaging

With ground effect cars, aerodynamic performance is closely tied to the chassis architecture and packaging. This was another area where McLaren excelled, demonstrating creativity and boldness through innovative solutions hidden under the bodywork. Unlike the extreme layout of the 2024 Red Bull, which caused some development headaches, the MCL39 delivered unmatched cooling efficiency, from brakes to the power unit. Its tightly packaged bodywork remained effective even in high temperatures, while rivals struggled to manage airflow, giving McLaren precious hundredths on the straights.

The MCL39’s front suspension system deserves special mention, being unique on the grid alongside Mercedes’ 2024 innovation. The integration between the steering rod and lower wishbone exemplifies the tight synergy between aerodynamics, mechanics, chassis, and vehicle dynamics, optimizing performance across all areas. This advanced architecture was overseen for the first time by Rob Marshall, a key hire from Red Bull, illustrating McLaren’s appeal to top engineering talent.

Tire management

The MCL39 excelled in tire management throughout the season, outperforming rivals to the extent that some speculated about illegal solutions. Attention, including from the FIA, was focused on brake duct designs, which regulate heat transfer between tire and wheel. McLaren mastered this area, but their work extended far beyond the brakes.

The car’s ability to control tire degradation reflects extensive tire knowledge, allowing the team to design a car that optimizes tire performance. Its well-balanced setup, minimal corrections, and controlled sliding helped maintain optimal temperatures. This capability highlights the excellence of McLaren’s trackside engineering, whose finely tuned setups extracted maximum performance from the MCL39 and made a decisive difference in a season decided by mere hundredths of a second in qualifying.

Power unit performance

While sometimes overlooked, the power unit played a crucial role. In a Formula 1 era with frozen development and minimal differences between the three main suppliers, choosing the right engine supplier was critical. McLaren’s 2019 decision to partner again with Mercedes proved invaluable. Six years later, the Brixworth power unit provided precious hundredths and even tenths of a second, which, combined with the numerous technical innovations of the MCL39, secured McLaren’s 10th Constructors’ Championship. Without Mercedes’ engines, it is hard to imagine McLaren achieving such success in an era where a tenth of a second can cost multiple grid positions—or more.