Hot air containing moisture in the car condenses into fog after being discharged from the exhaust pipe. It is a truth that there will be fog in winter. Driving in rainy days, reducing lane change, overtaking and other operations, is to reduce the probability of mistakes and accidents. At the same time, in normal weather, large trucks should avoid following the car at close range and parallel for a long time to avoid the influence of water vapor brought by the tires of large trucks.