In this study, the drag force measurements were carried out for a 1/32 scaled heavy vehicle model, consisted of truck and trailer, placed in the wind tunnel. The wind tunnel tests were also performed for 9 different free stream velocities in the range of Reynolds number between 113 000 and 453 000. The drag coefficients (CD) of the truck and trailer combination were experimentally determined. In the experimental studies, kinematic similarity was provided except moving road and blockage effect is ignored due to the small blockage ratio of 3%. The independence of Reynolds number was used for the dynamic similarity condition. The regions forming aerodynamic resistance on the truck trailer were determined and aerodynamic improvement was obtained with passive flow control methods. In the case of model 1 of truck and trailer, the aerodynamic improvement is obtained as % 15,71 by improving geometry of spoilers. % 22,46 aerodynamic improvements is also obtained by using passive air channel with a spoiler for the case of model 2. For the case of model 3, by adding a redirector to the model 2, the improvement is reached to % 25,58.