Racing
© Liauzh
George Russell’s early retirement at the Belgian Grand Prix gave Formula 1 rivals an unusually clear look at one of Mercedes’ most closely guarded areas, as the crane-lifted W17 exposed an underfloor and diffuser package that still plays a central role in rear-end downforce and stability.
Teams go to great lengths to hide floor designs because the underbody generates much of a car’s performance, even if the current rules make it a bit less decisive than before. That is why recovery shots matter. Sergio Perez’s Monaco qualifying crash in 2023 offered a similar opportunity when Red Bull’s RB19 was lifted into view, and while photographs never reveal every exact detail, they can give competing aerodynamicists enough to begin simulation work around the same ideas.
The Mercedes revealed at Spa showed the main building blocks of the modern rear floor. The diffuser remains the key device, expanding the airflow under the car to create a low-pressure area behind it and generate downforce. Around it sat the diffuser kick line, where the floor no longer has to stay fully flat, and the resin plank or skid block, which is there to stop teams running the car too low. If that plank wears by more than 1mm over a race, it is grounds for disqualification.
The images also showed the raised outer floor edge used as part of the FIA’s effort to limit downforce, plus outer diffuser elements that connect the wheel-hub aerodynamic area to the diffuser itself. Mercedes also had visible diffuser strakes to help manage the flow under the car, and one of the more revealing details was a diffuser "hole" that teams have explored this year to feed airflow across the full width of the diffuser.
That matters because the floor may be less sensitive under the current regulations, but it is far from simple. Small tabs were visible along the top edge of the diffuser, elements Mercedes had previously run in larger form before the FIA required the team to reduce them. The outer diffuser pieces also appear to be an evolution of last year’s brake-duct-mounted cascade winglets, extending the diffuser’s working area further rearward.
Other parts around the rear of the car showed how tightly linked the whole package is. The suspension members and the beam wing ahead of the diffuser are angled to help expand the low-pressure zone behind the car, and they work with the rear wing to maintain a high, consistent level of rear downforce. Inside the diffuser, the inner elements effectively act like extra strakes to keep the airflow under control as it exits the floor.
The current rules have opened up some of that design freedom. Under the previous regulations, the diffuser had to be more tightly enclosed to avoid disturbing the underfloor flow structures. With this generation described as less sensitive to flow separation, several teams have adopted the additional diffuser opening, allowing the air beneath the car to expand more aggressively at the rear.
Even so, managing that flow remains one of the hardest jobs on the car because of the floor’s length. Teams want the air under the car to stay energized and accelerating to offset friction losses, while also preventing separation as it reaches the diffuser. The slots visible at the rear corners of the floor, just ahead of the rear tires, are part of that fight. Mercedes had already modified that area for the Canadian Grand Prix to control tyre squirt, the turbulent air the rotating and deforming rear tires force sideways toward the diffuser.
That is the real significance of what Spa revealed. Even in a ruleset with reduced floor complexity, diffuser development is still critical because clean airflow at the rear gives the car a stable rear axle, protects downforce from tire turbulence and flow separation, and gives the driver the confidence to get on the power without sliding.