The present numerical analysis aims at studying the effect of changes in profile of truck-trailer on aerodynamic drag and its adverse effect on fuel consumption. The numerical analysis is carried out using commercial CFD software, ANSYS Fluent, with k-ω Shear tress transportation (SST) turbulence model. In present study four models of truck were analysed, including baseline model at different Reynolds numbers, namely 0.5, 1, 1.5 and 2 million. In order to enhance fuel consumption, various profile modifications have been adapted on baseline truck-trailer model by adding a spoiler and bottom diffuser at the rear of the truck, by providing vortex generator at the rear top of the truck and by adding boat tail at the end of trailer. The comparison has been done with respect to coefficient of drag, coefficient of pressure, pressure contours, and velocity vectors between all four cases. It is observed from the simulation results among different modifications of truck, adding of boat tail at the rear end of truck gives the maximum reduction in aerodynamic drag of 34.28 % as compared to baseline model, which reduces the fuel consumption by 20.57% at a speed of 82 km/h.