What can be used to solve the problem of not being able to see the rearview mirror due to fogged-up car windows on rainy days?

[LeElliot]

Here are some solutions for fogged-up car windows that obstruct the view of the rearview mirror on rainy days: Soap or toothpaste: Apply soap or toothpaste evenly on both sides of the car window. After it hardens, wipe it with a clean towel, and a wax layer will form on the glass surface. When rainwater hits the window, it will flow straight down, and no blurry water streaks will form on the glass. Anti-fog spray: Spray a small amount of anti-fog spray on both sides of the car windows and the rearview mirror. If the spray is uneven, you can use a towel or non-woven tissue to spread it evenly. Once the anti-fog spray dries, a protective film will form on the glass surface, effectively preventing fogging or water droplets. If the fogging is not severe, the effect usually lasts about a month. In fact, a mixture of water and dish soap has the same effect as anti-fog spray, but it doesn’t last as long. Maintain air circulation: Keeping the air inside the car flowing can reduce water vapor inside the vehicle. When there is a temperature difference between the inside and outside of the car, opening a small gap in the window ensures air circulation between the inside and outside. This allows the water vapor from breathing to flow out, significantly improving the fogging on the windows.