Its main function is to effectively reduce the air resistance when the car is driving at high speed and save fuel. According to the analysis of aerodynamic principles, we know that cars will encounter air resistance during driving, which can be divided into three aspects: longitudinal force, lateral force and vertical force. The speed of cars is directly proportional to the square of air resistance, so the faster the cars, the greater the air resistance. Generally speaking, when the speed exceeds 60km/h, the influence of air resistance on the car is very obvious. In order to effectively reduce and overcome the influence of air resistance when the car is driving at high speed, people have designed the tail wing of the car, which is used to make the air produce the fourth force on the car. That is, the adhesion to the ground, which can offset part of the lift, control the car to float, reduce the influence of wind resistance, and make the car drive close to the road, thus improving the driving stability. In addition to reducing the resistance in high-speed driving, installing a tail wing also helps to save fuel. Take a car with a displacement of 1.6 liter as an example. If the tail wing is installed, the air drag coefficient will be reduced by 20%, and the fuel consumption may not be obvious when driving on ordinary roads. If you drive on expressway, you can save fuel by about 10%.