Track surface roughness creates aerodynamic disruption that affected car performance unexpectedly in Malaysia.

Mercedes and McLaren struggled with car behavior at Malaysia's Sepang circuit due to aerodynamic effects from the extremely rough track surface, which creates disturbed airflow that doesn't behave smoothly along cars' surfaces. McLaren team principal Andrea Stella hinted that rough tarmac conditions make cars operate in weird ways beyond just tire considerations.

The phenomenon relates to how loose stones in rough surfaces generate disrupted airflow, causing moments when some cars don't have real-world performance matching the downforce teams see in data. This aerodynamic inconsistency was particularly prominent during the previous ground-effect era when cars were extremely sensitive to airflow disruptions.

Mercedes acknowledged their biggest issues occurred around parts of the track where Sepang's surface was most broken-up, particularly in slower corners. McLaren's prowess in high-speed corners from recent races wasn't evident in Malaysia, puzzling the team given their usual strong performance on demanding circuits.

The rough surface affects boundary layers and flow separation differently than teams can predict in simulations or wind tunnels. Mercedes deputy team principal Bradley Lord described their weekend as a complex three-dimensional problem involving the interaction of updates, track temperature, and surface characteristics that pushed the car outside its normal operating window.