Air resistance (along with rolling resistance) is the decisive factor which determines the dynamics of your car and its efficiency. The greater the air drag turns out to be, the more force is required to accelerate the car to a certain speed and to maintain that speed.
Air resistance is caused by displacement of the air surrounding the car. Due to the friction of this air on the vehicle surface, it pushes in the opposite direction to the movement of the car.
The formula for the calculation of air resistance is:
drag = car speed2 x front surface x drag coefficient x ½ air density.
The design of your SEAT model, including small gap and joint dimensions, reduces turbulence. This promotes low air drag and consequently low fuel consumption and fuel costs. Nonetheless, the most important factor in air drag is the car speed. For example, doubling your speed multiplies air drag by four.