In commercial vehicles, the greatest challenge is to improve the fuel economy and reduce emissions. The Aerodynamic drag control is one of the best ways to do the same. In Tractor-trailer assembly, the gap between the cabin and trailer and also rear end of the trailer are the critical areas which will affect the coefficient of drag drastically. Also the low pressure at the rear end of the trailer is one of the reasons for rear collision of trucks with other vehicles. The main objective of this work is to incorporate the inflatable boat tail at the rear-end of the trailer to reduce the drag coefficient and also to act as energy absorber in case of rear impact. The generic model of commercial vehicle with various boat tails is designed in CREO software and both steady and unsteady analysis are carried out by using ANSYS Fluent under various conditions from 0 to 6 degree wind directions. The simulation results are validated with wind tunnel test on the 1:40 scaled model of commercial vehicle with and without boat tails. The result shows more than 18% reduction of drag coefficient with boat tail and the boat tail is absorbing the impact energy while rear impact. Keywords: Commercial vehicle, Coefficient of Drag, Inflated boat tail, Energy Absorber, Wind Tunnel.