The rapid advancement of technology and the increasing speed of vehicles have led to a substantial rise in energy consumption and growing concern over environmental pollution. Beyond the promotion of new energy vehicles, reducing aerodynamic drag remains a critical strategy for improving energy efficiency and lowering emissions. This study investigates the influence of key geometric parameters on the aerodynamic drag of vehicles. A parametric vehicle model was developed, and computational fluid dynamics (CFD) simulations were conducted to analyse variations in the drag coefficient ( $C_{\text{d}}$) and pressure distribution across different design configurations. The results reveal that the optimal aerodynamic performance—characterized by a minimized drag coefficient—is achieved with the following parameter settings: engine hood angle (α) of 15°, windshield angle (β) of 25°, rear window angle (γ) of 40°, rear upwards tail lift angle (θ) of 10°, ground clearance (d) of 100 mm, and side edge angle(s) of 5°. These findings offer valuable guidance for the aerodynamic optimization of vehicle body design and contribute to strategies aimed at energy conservation and emission reduction in the automotive sector.