The drag force acting on the vehicle has a significant role in the braking efficiency of the vehicle. The braking efficiency is directly proportional to the drag force acting on vehicle. Using add-on gadgets on the vehicle, the drag force can be enhanced. This paper deals with the effect of an additional air drag braking system on drag force of a passenger car. The drag force and drag coefficient of a passenger car is estimated by using Computational Fluid Dynamics (CFD) analysis. An increase in the drag force is observed to the attachment of an additional air drag braking system. In order to optimize the dimensions of the drag braking system for the highest drag force, Taguchi Optimisation is performed. It is found that optimized drag braking system improves the braking efficiency of passenger car. The experimental analysis is performed on a clay model of a passenger car with reduced scale 1:16 in a wind tunnel. It is found that the amount of braking effort is reduced significantly due to the application of this new concept, air drag braking system. The numerical analysis results appear to be in good agreement with those from experimental analysis. © 2022