McLaren MCL39: the development path of the world championship-winning car
If McLaren managed to preserve and build on the competitiveness of the excellent MCL39, much of the credit also goes to the updates introduced throughout the season. The MCL39 was the undisputed reference car of 2025, the machine that brought the Drivers’ World Championship back to Woking after 17 years and confirmed the Constructors’ title already celebrated the previous season.
McLaren arrived at the start of the championship with the strongest overall package on the grid, and then succeeded in consolidating that advantage during the middle phase of the season thanks to a carefully planned development programme. Below is a detailed look at the main stages in the evolution of the world champion team’s car.
Aerodynamics
McLaren adopted a very methodical approach when introducing updates, always taking the necessary time to verify proper correlation between simulation and track performance. This was part of the work on fundamentals that team principal Andrea Stella mentioned on several occasions throughout the season.
In Saudi Arabia, for example, the MCL39 ran with new components on the rear wheel assemblies and at the diffuser, but these changes were not raced. They were experimental parts designed to gather data and support future developments rather than deliver immediate performance gains.
One of the most significant outcomes of this process was the new floor, evaluated during Friday practice at Silverstone and then raced from the Belgian Grand Prix onwards. Notably, this was the only floor evolution introduced during the season, placing McLaren against the trend set by its rivals. Red Bull, by comparison, produced as many as six different floor specifications over the same period.
Despite this, the Woking-based team invested across the entire car, with particular attention paid to the front end in order to optimise airflow structures feeding into the new floor. These changes were designed to work in conjunction with other updates. A key example was the front wing introduced in Canada, which arrived after the clampdown on flexibility tests in Barcelona. McLaren managed to comply with the revised tests without altering the wing’s geometry.
Further front-end aerodynamic work included the reshaping of the front suspension arms in Austria, which were refined again for the Italian Grand Prix.
Brake ducts
McLaren was among the teams that invested most heavily in brake cooling ducts, continuing a development trend seen in previous seasons. The front brake inlets were updated at the Australian and Austrian Grands Prix, excluding the specific adaptation required for the unusual layout of Monaco.
The rear brake ducts, meanwhile, were modified at Imola, Austria and Silverstone. Under the regulations, the team was only required to declare visible updates, but it is plausible that internal changes to the brake drums were also introduced during the same events.
Work in this area goes well beyond the search for maximum cooling efficiency. The goal is also to manage heat flows between the tyre, the wheel rim and the brakes, allowing for better control of tyre temperatures. It is no coincidence that the brake drums have often been cited as one of the reasons behind the excellent rear tyre degradation management shown by the MCL39.
The wing package
The reigning world champions started the season with two different rear wings, both of which were already used during winter testing. The V-shaped version featured prominently in the opening quarter of the championship, while the higher-downforce configuration was deployed from Zandvoort onwards.
Over the course of the season, McLaren introduced additional specifications, bringing the total number of rear wings to six and giving the MCL39 impressive versatility across different circuit types. At Imola, for example, a medium-low downforce wing made its debut, while Monaco saw the introduction of the maximum-downforce version.
There were also two particularly low-drag configurations introduced at Spa and Monza. For these events, the team also brought a new beam wing and new flaps for the front wing. In doing so, McLaren continued the development path started in 2023 to improve efficiency in low-downforce trim, historically a weak point of the Woking car.
Suspension development
Updates to the MCL39 were not limited to aerodynamics, as mechanical components were also refined. In Austria, for instance, a slightly revised rear suspension made its debut. However, the most important change concerned the front suspension, which was introduced one race earlier in Canada.
This modification was designed to improve the transmission of forces from the front axle to the steering wheel, giving the driver a clearer feel for the behaviour of the front tyres as they approached locking under braking.
Lando Norris was the only driver to choose to run the new suspension, explaining that he is a driver who feels the car mainly through his hands. This also contributed to his early-season difficulties with the revised steering layout of the MCL39. Oscar Piastri, by contrast, consistently refused to test the modification, stating that he had never experienced that type of issue. It remains an open question whether the Australian, with hindsight, might have made a different choice.
The development of the McLaren MCL39
Australia: front brake cooling ducts
China: rear wheel assembly appendages
Bahrain: front wheel assembly deflectors
Saudi Arabia: diffuser and rear wheel assembly appendages
Imola: rear brake ducts, rear suspension arm fairings, rear wing, beam wing, front suspension modifications
Monaco: rear wing, beam wing, front suspension modifications, enlarged front brake ducts
Canada: front wing, rear wing, front suspension modifications
Austria: front suspension fairings, front brake ducts, rear brake ducts
Silverstone: floor, rear brake ducts
Spa: rear wing
Monza: rear wing, beam wing, front wing flaps, front suspension fairings
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