The aerodynamic performance of a simplified prototype vehicle using wind tunnel experiments and numerical simulations are highly investigated. The primary aim of this study is to improve the aerodynamic efficiency of a car model of 2017 Lamborghini Aventador LP 750-4. Local flow velocity filed, pressure distribution, and aerodynamic parameters such as drag and lift coefficients are measured over a wide Reynolds-number range for two cases, with and without using rear wing. Compared to the baseline model, the modified design achieves a drag reduction with and without using rear wing by 7.9% and 7.6% numerically and experimentally, respectively. A good agreement between the numerical drag coefficients in the present study for the baseline car model and the experimental data has been achieved with and without using rear wing by 3.39% and 2.98%, respectively. These findings ascertain that targeted geometric modifications can significantly reduce drag in ground-vehicle applications and provide guidance for future aerodynamic design.