The 2025 Mercedes faces the challenging task of improving upon the four-race wins achieved by its predecessor. While the W15 proved significantly better than the Silver Arrows from earlier in the ground-effect era, it was not without issues. Problems such as bouncing, rear-end instability, and balance offer key opportunities for growth, prompting the Brackley-based team to target both aerodynamic and mechanical solutions.
The starting point
The W16 will evolve from a solid foundation set by the W15. The progress made compared to the troubled Mercedes cars of the first two years under the new regulations is credited to a reorganization of the technical departments, once again under the leadership of James Allison. This restructuring also addressed errors in preparing CFD meshes, leading to a new approach for aerodynamic simulations with greater emphasis on different physical aspects. This shift has allowed Mercedes to filter and develop solutions through an entirely new concept.
The changes extend far beyond abandoning the zeropod concept, altering how the car generates load and aerodynamic efficiency. As team principal Toto Wolff put it, “The foundation of this car is more conventional in how it generates downforce and efficiency.” After the overly high ride height of the 2023 car, shaped by the porpoising challenges of 2022, the W15 operated closer to the ground. To handle the revised ride heights, the team introduced innovative suspension systems, including a futuristic push-rod rear suspension. Despite generating significantly more downforce than its predecessor, the drivers struggled at times to harness it effectively. “We measure much more downforce than what translates on the stopwatch,” Allison remarked earlier in the year, highlighting the areas requiring attention for 2025.
Balancing act
The primary limitation of the W15 lay in its balance, as it was competitive in either high-speed or low-speed corners but never both at once. This shortcoming stemmed partly from a lack of correlation between real-world data and simulations. “There’s something we can improve in our simulation models regarding the balance between high and low speeds because that’s where we see differences between the factory and real life,” Allison explained at the season’s start.
The breakthrough came mid-season when Allison resolved the balance issues, as Toto Wolff revealed in July: “Thanks to Allison, there was a moment when the data finally made sense. The main focus was on how we balanced the car.”
The adjustments triggered a chain reaction. With balance restored, the car experienced less sliding, enabling the tires to operate within their optimal temperature window—at least in cooler conditions—leading to significant performance gains. “These weren’t major changes, but they made an enormous difference in lap times,” George Russell observed after the team’s triumphant British Grand Prix weekend. However, the W15 still suffered from a narrow balance window, excelling on circuits with uniform corner types, such as Las Vegas, Montreal, Silverstone, Spa, and Qatar, but struggling elsewhere.
The importance of mechanics
The precarious balance stemmed from hidden challenges in the aerodynamic map. From the outset, Allison acknowledged the possibility that “the characteristics of the suspension could exacerbate these issues,” adding, “To address everything properly, you have to change them.” At high speeds, balance is more influenced by the center of pressure—the distribution of aerodynamic forces—while slow-speed performance depends heavily on mechanical factors and the center of mass.
Mercedes has struggled over the past two years to integrate mechanical and aerodynamic balance effectively. Even the sudden turnaround during the Spa weekend, transitioning from early struggles to a Sunday victory, stemmed from aligning mechanical setups with expected car behavior. “It was about a mechanical alignment with how we expected the car to perform,” Wolff noted at the time.
For the W16, planned suspension updates—both internal and external—aim to address the rear-end instability tied to overheating tires. “It’s simply a problem with rear tire temperatures, and much of our attention is focused there,” said trackside engineering director Andrew Shovlin. “It’s related to how the car is set up, so you may need some mechanical tools to help change that.”
The W15’s optimal performance in cooler conditions, as seen at Silverstone and Las Vegas or during wet qualifying sessions in Montreal and Interlagos, highlights this issue. For the W16, the goal will be to maintain tire performance as asphalt temperatures rise. “It’s not the kind of problem you can fix with a single aerodynamic update,” Shovlin clarified, suggesting structural interventions for 2025.
Height control
Work on these issues began as early as 2024. Data from the Austrian Grand Prix revealed a significant step forward, with a noticeable bulge on the car’s nose hinting at updates to the front suspension. This likely involved a new anti-dive damper to stabilize the floor and optimize aerodynamic performance at consistent ride heights. “We’ve also worked on the mechanical package,” Allison confirmed later in Hungary.
Height control remains a critical development area for a car designed to run low and stiff. While the W15 excelled on smooth tracks like Silverstone and Qatar, it struggled on bumpier surfaces such as Austin and São Paulo. Lowering the car also reintroduced bouncing issues. Early-season races in Jeddah, Suzuka, and Melbourne, with their high-speed corners, were particularly challenging, though they allowed the team to experiment and learn to manage the phenomenon. However, bouncing persisted through the season, making it another priority for the W16.
Slow corners under scrutiny
Aerodynamic updates to the W15 helped guide development for 2025. For instance, a new front wing introduced around Monaco and Montreal represented a departure from the original philosophy, resulting in a more balanced and driver-friendly car. However, not all updates were successful; the floor introduced at Spa was abandoned due to its negative impact on drivability. The final Austin package met expectations, delivering increased downforce without disrupting airflow beneath the floor.
While the 2024 development focused on improving the W15’s efficiency, it didn’t resolve its chronic issues. One such problem was poor performance in consecutive low-speed corners, where the car’s rotation required greater rear-end stability than it could provide. “We didn’t expect this update package to address that issue,” Shovlin admitted after Austin. The W16 will need to free Mercedes from these limitations, aiming to close the ground-effect era with championship titles in sight.
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