Within the course of their experiments, they uncovered many different types of aerodynamic drag on vehicles. In addressing these disparities, they came up with various modern designs to also help to reduce drag. Moreover, it can be seen that dissimilarities existed in the differences between racing car design and road car design, which had led them to explore the reasons why road vehicles did not look like racing cars. This paper will investigate other factors, such as European legislation, that influences the appearance of road vehicles. In addition, it will discuss how and why the appearance of modern cars changed in recent years through the use of texts, pictures, graphs, equations and diagrams. Moreover, the role of Bernoulli relationship on the flow around an object will be explored as well as an explanation of boundary layer properties. Finally, it will analyze flow control using passive methods like vortex generators. Clearly, researchers in their investigations had devised innovative ways to reduce the aerodynamic drag of modern road vehicles.
Bettes (1982) defined aerodynamic drag as occurring when a car moved through air and the energy that opposed its direction and slowed down its movement. Another more comprehensive definition of aerodynamic drag was: ”The resistance of the air to forward movement, sometimes called "aerodynamic drag". This is a factor of the shape of the vehicle, the objects which stick out (i.e., mirrors, mufflers, bumpers), the amount of turbulence at the rear of the vehicle, the nature of the vehicle's skin surface, and the amount of air going through the vehicle for cooling and ventilation. The faster you go, the greater the air friction (proportional to velocity²). At the same time, the power to overcome such friction is proportional to velocity³.” (www.f1technical.net/glossary/). ...