Car windows fog up when the glass is cooler than the air inside the auto. This commonly happens during the winter months. The windows can also fog up when you run the air conditioner constantly during hot-weather months. The windows become cooler than the air outside the car. The fog can make it difficult to see when you're driving. You can use the defroster, or wind the windows down a little or turn on the air conditioner to regulate the temperature of the windows and the air inside the car. Or use a simple trick to prevent your windows from fogging up in the first place.
Spray window cleaner on the glass. Then wipe the surfaces clean with cloths. According to Techskipper.com, dirty car windows fog up more easily than clean ones. The dirt gives the condensation a rough surface to stick to.
Squirt a few drops of baby shampoo onto a clean cloth, according to FC&A Publishing. Wipe the shampoo over the inside of the windshield, side windows and rear window. Apply more shampoo to the cloth as needed. Wipe the glass until it's clear.
Reapply the baby shampoo as directed to each car window every couple of weeks. Follow the above instructions to achieve the best results.
You can use any type of hair shampoo, according to FC&A Publishing. However, tear-free baby shampoo works the best to prevent fog on glass.