At Woking, McLaren has taken the concepts that made the MCL38 a winning car to the extreme. Since this year’s F1 cars run underweight, instead of simply adding ballast to the front wing and nose, Technical Director Rob Marshall preferred to redistribute mass where it could generate actual performance gains. The team’s attention has particularly focused on thermal management with a system designed to support aerodynamic efficiency.
So, what exactly is McLaren’s secret? Perhaps there isn’t a single mystery to unravel; their technical superiority might simply stem from an overall better car project across multiple areas. This allowed Rob Marshall and Aerodynamics Director Peter Prodromou to push the principles of the MCL38—last year’s Constructors’ Championship-winning car—even further.
If this is the case, it becomes clear why replicating Woking’s solutions is so difficult. Several teams have based this year’s cars on some McLaren concepts, but only Max Verstappen with Red Bull has come close to the MCL39’s performance. At Red Bull, engineers in Milton Keynes resisted the temptation to compromise the RB21 by introducing external ideas, while other teams remain far behind. For example, in Mexico, Lando Norris on the McLaren outpaced Charles Leclerc in the Ferrari by half a minute.
The high-altitude Mexican Grand Prix, at over 2,200 meters with very thin air, highlighted a key characteristic of McLaren: while most teams opened hot air vents that reduced aerodynamic efficiency, the papaya car maintained a very tight, closed bodywork. This is remarkable considering that, with the same Mercedes power unit, other teams’ engine covers have turned into virtual Swiss cheese, with massively enlarged rear vents—just look at the W16 from the works team, along with Williams and Aston Martin.
Andrea Stella, McLaren’s Team Principal, had already highlighted the importance of thermal management at the Autosprint “Festa dei Caschi” last winter. He explained, “The entire cooling system has been redesigned. Compared to 2024, nothing remains unchanged. The layout has been made much more efficient, allowing us to run tighter aerodynamic configurations even in extreme conditions. There is a millisecond gain, at the same temperature, which becomes substantial.”
Heat management extends beyond just the power unit; it also affects the ability to prevent rear tire overheating. This is achieved through carbon ducts in the corners designed to create a channel of fresh air, preventing thermal transfer from the brakes to the tires. A glance at the complex corner ducting reveals how much time Woking’s engineers have invested in this solution, with versatile options to adapt the system to different circuits.
Authoritative paddock sources praise the high quality of Rob Marshall’s work, starting with the MCL38. The technical director had a car that was significantly underweight (800 kg with driver) and, being rearward-oriented, required a lot of front ballast to achieve correct balance. Instead of loading the front wing and nose with excessive ballast, Marshall’s team redistributed weight through careful project choices. Contrary to expectations, McLaren may have increased radiant mass, improving thermal exchange within the sidepods and under the engine cover, while keeping bodywork openings minimal to maximize aerodynamic efficiency.
The saved weight was therefore “reinvested” in areas that enhance performance: the previously mentioned corner ducts, and possibly the suspension. The front pull-rod suspension, with the steering arm located behind the lower wishbone, is an example of a highly sophisticated design created for the advantage of Prodromou and Aerodynamics Engineer James Pesce.
In short, to reach minimum weight, McLaren redistributed mass in critical areas of the MCL39 while still retaining the necessary ballast to balance the car across diverse circuits. It is therefore not surprising to see multi-layer water radiators mounted above the power unit, leaving other cooling packages in the sidepods, a departure from the usual distribution layout.
It seems that flexible wings, another development topic for the MCL39, served as a useful distraction. Not that Woking hasn’t explored solutions at the limits of the regulations, but likely, performance differences versus rivals were not generated in that area. Following the stricter static tests on front wing deflection introduced at the Spanish Grand Prix, McLaren experienced no performance drop, indicating that the truly “hot” points lie elsewhere.
With a competitive advantage in hand, the Woking team has sought to maximize it. It will be fascinating to see how much of this layout can be carried over to the 2026 car, which aims to shed 30 kg compared to this year’s ground-effect F1 cars.
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