The start of McLaren’s season has caused a real shock, offering two opposite and unprecedented interpretations in the team’s recent history. It is highly unusual to see a top team from 2025 struggling even to line up on the grid.
But it is equally surprising to see a car feature a fundamental design parameter that diverges so drastically from the competition: we are referring to an extremely short wheelbase. The technical revolution introduced by the FIA for 2026 a mandatory drastic reduction in wheelbase, dropping from 360 cm to 340 cm.
A move that met with unanimous approval from drivers and fans alike. Parallel to the physical dimensions, the underbody aerodynamics have been completely overhauled, significantly reducing the ground effect. With the “ground effect cars,” teams were forced to exploit the full 360 cm limit to maximize the length of the Venturi tunnels.
Conversely, on the 2026 cars, this necessity has vanished, as the area tasked with generating floor downforce is now highly restricted and standardized across the board. Another challenge imposed by the FIA concerned weight, with a 30 kg reduction; a logical step on paper, given the smaller dimensions.
However, this parameter has made life harder than ever for the designers. The current Power Units (PU) weigh about 34 kg more; furthermore, advances in safety, with more stringent roll hoop tests and the new two-stage frontal crash test, have added further mass. The result is a total weight increase of approximately 64 kg.
Meeting this minimum mass parameter has been a true nightmare, especially considering that 10 kg of weight can cost from 2 to almost 4 tenths of a second per lap, depending on the track. In this scenario, the overall length of the car becomes the crucial variable for saving weight.
This is also why we have returned to seeing very distinct cars, featuring unprecedented solutions in various areas and differing wheelbase dimensions. It was impossible to make a reliable assessment based on the official launch images, considering that photos and renders are heavily retouched before release.
Between Bahrain and Australia, however, thanks to targeted pictures and teamwork with Camillo Morande, the author of my animations in recent years, we put together a comparison of the “class leaders.”
The 3D analysis confirmed what emerged from initial visual impressions during the closed-door Barcelona tests: the McLaren MCL40 is the shortest car on the grid. Up until the 2024 season, this type of analysis was conducted much more precisely at the Hungarian GP, but that is no longer possible today.
Indeed, the recent renovation of the circuit, which took place last year, eliminated the media centre above the pit garages and, consequently, the terrace that was perfectly level with the scrutineering area.
That terrace represented a “secret” and highly useful vantage point for taking uniform photos. The cars were inevitably placed in the exact same position because they had to be centered on the FIA’s four fixed weigh scales, sitting stationary for a few moments during technical scrutineering.
A much severe measurement method compared to the one used on track between Bahrain and Australia. In Budapest, you only needed a lot of patience, waiting for the cars to reach the weighbridge. Analyzing the top five cars, the biggest surprise came from McLaren: The MCL40 measures about 15 cm less than the 340 cm wheelbase limit, so 35cm less than MCL39.
An exceptional figure, unseen among the competition thus far even in the past. This average measurement was confirmed by both Andrea Stella and Rob Marshall. The choice is a bold one: the wheelbase reduction was achieved by moving the rear axle closer to the chassis, without altering the distance between the front axle and the cockpit, or the leading edge of the sidepods, which remains in line with that of their rivals, as shown by the comparison with the SF-26
The front axle position is crucial for pushing the front tyre wake (turbulence) as far away as possible from the leading edge of the sidepods, improving both aerodynamics and cooling.The approximately 15 cm reduction is achieved by compacting the gearbox casing and spacer assembly. The solution should guarantee an advantage across all tracks, although it required a complete redesign of both the cooling system and the aerodynamics of the sidepods and engine cover.
The position and dimensions of the heat exchanger above the engine have remained largely unchanged, while the sidepod radiators have been significantly repositioned. On the MCL39, the radiator core was narrow and very long, more so than on any other car, as the images highlight.
Its positioning was far less inclined compared to the wider, shorter radiator we see on the MCL40. Consequently, the shape of the sidepods and the thermal management approach have also changed. The MCL39 featured small cooling louvres on the side of the engine cover, as well as a very narrow central cooling exit at the rear of this component.
Cooling efficiency was one of the MCL39’s strong suits, even compared to Mercedes. On the MCL40, the engine cover is completely closed at the sides, while the central exit has been enlarged.
