Abstract: When objects move through air, forces are generated by the relative motion between the air and surfaces of the object. Aerodynamics is the study of these forces, generated by the motion of air, usually aerodynamics are categorized according to the type of flow as subsonic, hypersonic, supersonic etc.

Aerodynamic analysis of passenger vehicle exterior body has been an important area of interest since the time of the invention of automobiles. Initially, the analysis was done by making a complete car and running it on track. But measuring the experimental parameters was very difficult in external uncontrolled environment and also during the development stage there is no actual car to test so testing had to be done after an anticipated model of the car had been developed. The designers had to retrace the entire design process if they encountered any flaws in road test.
It is essential that aerodynamics be taken in to account during the design of cars as an improved aerodynamics in car would attain higher speeds and higher fuel efficiency. For attaining this aerodynamic design the cars are designed lower to the ground and are usually sleek in design and almost all corners are rounded off, to ensure smooth passage of air through the body , in addition to it a number of enhancements like spoilers, wings are also attached to the cars for improving aerodynamics. Wind tunnels are used for analyzing the aerodynamics of cars , besides this a number of software‟s are also available now days to ensure the optimal aerodynamic design.