Question

Why does air friction affect a car' s gas mileage ?

Answer 1

Air friction does not significantly affect a car's gas mileage. Air turbulence does. Whereas air friction is the opposing force caused by air rubbing sideways along a surface, air turbulence is the act of stirring up the air and creating pressure differences. Cars are slowed down when they stir up the air too much. Stirring up the air creates vortices and billows that take energy away from the car. This effect is known as "wake drag", "pressure drag", or "form drag".

Answer 2

because air tries to stop the means it is pressureing the car so car's engine needs to generate more power to overcome the pressure thus it's milage affect