The principle of race car design is similar to the one that flies the airplane. The only difference is that in case of airplane wing or airfoil is shaped upward whereas in case of race car the wings are mounted upside down. The difference in the direction of the wings is because the airplane needs a lift and a race car needs a downforce. In any case, both work on the principle of aerodynamics, a refined form of science that studies the affect of air on a moving object.

Earlier aerodynamics was only restricted to race cars like those in F1 cars but these days’ high-end luxury cars like BMW and Audi are also adorned with aerodynamic design specifications in order to improve performance and mileage.

The two basic principles of car aerodynamics are drag and downforce. These define the speed, control, and even mileage of any car.

Drag

Some energy is required by cars to move through the air. This energy is used in overcoming a force known as drag.

When there is air resistance, the measurement of drag helps to define complex dependencies of shape and inclination. This measurement is known as drag coefficient which is calculated experimentally through

Cw = W/A v2* Q/2

Where, Cw is drag coefficient, W is air resistance, A is cross-sectional area, V is driving speed, and Q is air density.

In car aerodynamics, drag actually comprises of two forces, frontal pressure and rear vacuum. Frontal pressure is generated by the air that attempts to flow around the front of the car. As air moves towards the front grille or bumper, the air molecules begin to compress and increase the air pressure at the front of the car. This puts extra pressure on the engine to run the car, so if the front is sleek, the air pressure distributes along the sides of the car, thereby increasing the speed of the car.

Rear vacuum pressure applies to the hole that a car leaves behind in the air while moving. The boxy structure of the car creates a bigger vacuum behind the car and the air molecules are not able to fill in the empty space. This creates an opposite force which increases the force required to overcome the air resistance. The inability of air molecules to fill the space is known as flow detachment which creates turbulence. Therefore, the entire length of the car needs to be modified to support the aerodynamic structure of the car.