McLaren MCL39: aerodynamic upgrades debut in F1 Jeddah to boost performance. McLaren introduces its first MCL39 upgrade in Jeddah.

McLaren arrives in Saudi Arabia as the championship leader in both the Constructors’ and Drivers’ standings. To try and widen the gap with their rivals, the team in Woking has introduced a new diffuser to extend the McLaren’s operating window also in Jeddah. In our analysis and gallery, we take a look at how Lando Norris and Oscar Piastri’s car changes for the Saudi Arabian GP.

At the fifth round of the 2025 Formula 1 World Championship, McLaren has approved the first step of upgrades to the MCL39, the benchmark car at this stage of the season. With a design that follows the continuity of the MCL38, the engineers led by Rob Marshall have worked meticulously to optimize vortex extraction beneath the car.

Compared to the “original” version of the MCL39 used in the first four races, the updated diffuser spec changes slightly at the trailing edge. Although the visual differences are minimal, the aerodynamic benefits are numerous. With increased expansion capability linked to a redesigned bend geometry, the MCL39 now expands the air more efficiently and generates more downforce.

McLaren tackles drag in Jeddah
Alongside this improved expansion, the interaction also improves with the components surrounding the diffuser, such as the beam wing and the rear wheel corners. These parts, adjacent to the diffuser and actively involved in generating downforce, have been modified to suit the track.

The Jeddah circuit presents a significant technical challenge, as it is a high-speed track with long straights where low drag is crucial. To address this, McLaren has chosen to carry over components from the MCL38. These include the rear wing, which debuted in Brazil in 2024, and a very low-drag beam wing configuration.

Only the lower element of the beam wing features a relatively long chord and an angle suited to extending the diffuser and increasing the downforce generated by the floor. The second, upper element is almost flat, aiming to minimize aerodynamic impact and reduce the drag on the MCL39. This step is almost necessary to counter a drag level that appears to be inherent to this new McLaren chassis, which may have aerodynamic penetration as a technical limitation.