The MCL39 made its on track debut in a camo papaya and black one-off livery ahead of the launch of the real design at the F1-75 event on February 18th. With this came select pictures from the team, which, while they’ve perhaps been selected to retain some secrecy around their full car concept, do give us our first insight into the development direction they’ve gone in.

Though we expect 2025’s cars to be an evolution of last year’s as we reach the conclusion and peak of what’s possible under these regulations, with the competition so tight teams who want to run at the front are left with little option but to push development as far as they can.

McLaren have done just that in their opinion, with Andrea Stella saying “everything has been subject to optimisation. Sometimes incrementally, sometimes actually quite substantially.”

Though we can only go on what we can see, Stella made clear to the media that this optimisation goes beyond what’s visually changed as they push their concept to its limits.

“This car is innovative, pretty much every fundamental component of the layout has been subject to some innovation in order to gain…sometimes not only by marginal gains, some technical opportunities for development.”

So how have they done this? Let’s run through the visual differences between the MCL39 and the MCL38…

Front Suspension

McLaren have put a focus on increasing the anti-dive of the car through altering the front suspension – aiming to give the car more stability under braking, giving the driver more confidence. They’ve done this by lowering the pickup point of the rear leg of the upper wishbone, bringing it almost in line with the front leg. Aerodynamically, this also optimises the air flow over these components and to the front of the underfloor and sidepod – in line with Stella’s comments about most of the optimisations being for aerodynamic purposes over mechanical. 

The steering arm has also been placed with a steeper incline towards the chassis which will also clear a bigger space behind the front wing for improved airflow to the front of the floor.

Rear Suspension

In combination with the anti-dive measures at the front, the team have introduced more aggressive anti-lift through alterations to the rear suspension. Though the rear suspension is harder to see through the images, the forward leg of the upper wishbone pickup point looks to be mounted lower to achieve this anti-lift effect. 

Sidepod Inlet & Sidepod Shape

For the MCL39, McLaren have moved away from the letterbox shape cooling inlet that was seen on their previous car and towards a backwards-P shaped inlet, like was seen on the Mercedes W15. The approach of having a simultaneous horizontal and vertical inlet in this area is one that was also used by the SF-24 and RB20 too.

The sidepod of the MCL39 also appears to be more rounded in the mid-section than its predecessor, increasing its width but decreasing its depth, allowing for a revised and bigger undercut. 

This is a similar design to what was seen on the Ferrari SF-24, along with a more linear upper sidepod/engine cover area – a departure from the curves in this area that featured on the MCL38. This not only allows the air to flow to the beam wing without impacting that to the rear wing, but also increases the amount of air flowing through the area between the rear tyre and rear floor to the diffuser.

Airbox

The airbox has moved from being a taller circle shape on the MCL38 to a flatter oval on this new car, perhaps resulting from some weight saving efforts in the roll hoop area while also lowering the car’s centre of gravity.

Smaller details

The wing mirror mount support point has shifted outwards to the very edge of the tray over the sidepod inlet, presumably for a small aerodynamic benefit. There’s also a new winglet at the side of the halo.

Flexi wings?

Interestingly, given the current conversations around the incoming flexi-wing technical directive, the front and rear wings are one area of the MCL39 that appear to be consistent with the MCL38.

As part of this TD, the static load tests will be made more stringent for the rear wing from the opening round onwards while the allowed deflection for the front wing will reduce from the ninth round in Barcelona.

McLaren were one team widely thought to have capitalised on the benefits that flexibility in this aerodynamic bodywork can bring over the 2024 season, perhaps beginning with the front wing in Miami and on their low-drag rear wing used in Spa, Monza and Baku.

As such, it was a subject of the media’s questioning of Andrea Stella at the MCL39 launch with Stella revealing that the new TD had given them “no headache at all” at this point of the year to Sky Sports.

However, from the ninth race onwards “small adjustment” will be required, in Stella’s words, perhaps indicating that these wings on the MCL39 are carryovers of those used in the later stages of 2024. This may be especially true for the front wing, given the FIA’s green light to the use of flexibility there at the end of the 2024 season.

The rest of the year…

Bringing year long upgrades is an area where McLaren excelled in 2024, with almost every upgrade package brought to the car working from the outset. Despite this though, their MCL38 began the year underdeveloped until the pivotal Miami upgrade package, which had a clear impact on performance. So is it justified to have concerns over this happening again, especially given the upcoming 2026 regulation overhaul?

Stella said, “We have not changed the approach or the rate of development with a front loading of our developments.”

“We’ve just tried to go as fast as possible in terms of developing the car, which means there will be some upgrades during the early races of the season,” he explained. “But this would have been the same even without a ‘26 change of regulations looming ahead.”

The level of competition, especially at the back end of last year, has informed this approach.

“We’re just going as fast as possible because we’re very aware that last season, even if it’s been a successful season, the margins we have from a performance point of view meant we needed to be aggressive with the car and try to cash in as much performance as possible.”

“…had we not gone as fast as possible in terms of development, we might very quickly lose any advantage that we had,” he added.

The first on track feel

It’s always tough for the drivers to get a full picture of their new car from a 200km shakedown in a cold and often damp Silverstone, but Lando Norris was reassured that the changes made over the winter hadn’t impacted performance negatively.

“It felt normal, I’d say,” he said. “So that’s been the first good step, because they have been quite innovative with some of the designs and some things that they tried to attack with the car this year.”

The MCL39 will be back on track for pre-season testing in Bahrain from February 26-28th before the first competitive round of the year in Australia from March 14th.