Aerodynamic drag reduction of road vehicles has become the main focus to develop fuel-efficient vehicles. Among various techniques to reduce aerodynamic drag, the underbody modification of vehicle was a less explored method. This study was an attempt to understand the effect and relation of underbody modification on aerodynamic drag of vehicle by solving three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations. In the present study, simplified car geometry with wheels was generated. The vehicle rear underbody was modified by slicing at certain angles to direct the underbody flow to the rear of vehicle in order to reduce the pressure difference between the front and rear of vehicle. Commercial computational fluid dynamics (CFD) software ANSYS Fluent 17.1 was used to simulate the flow. k-ω SST (shear-stress transport) model was chosen as the turbulence model. It has been found that the pressure difference decreased as the wake produced by the wheels was restrained from getting mixed with the wake of vehicle. Drag reduction of 8.2% was achieved by just sweeping the rear underbody. It was evident that redirecting the flow from underbody to the rear of the vehicle can contribute in developing aerodynamically efficient automobiles.