The road transport sector, a major consumer of global energy, relies predominantly on oil-based fuels and contributes significantly to greenhouse gas emissions. Enhancing fuel efficiency through improved vehicle aerodynamics is essential for sustainable mobility. However, crosswind disturbances compromise aerodynamic performance by increasing drag and rolling resistance, particularly for heavy-duty vehicles. This study investigates the impact of extreme crosswind on vehicle energy consumption and dynamic behaviour by considering driver steering response under extreme conditions at different delay times. A two-way coupled aerodynamic and vehicle dynamics simulation framework is employed to capture these interactions. The findings highlight the critical role of driver skills, i.e., prompt steering by driver effectively mitigates energy losses, whereas delayed or abrupt corrections exacerbate rolling resistance through pronounced tyre slip angles. For example, delayed steering response of the driver (e.g., 1.0 second delay) increases energy consumption by 77% when compared to 44% maximum increase for prompt steering of the driver. These results underscore the complex interplay between aerodynamic forces and driver-induced dynamics in shaping vehicle energy efficiency under crosswind conditions.