Warm, wet air inside the cabin hits cold glass. Water condenses. You get fog. If wet mats, umbrellas, gym bags, or leaky seals keep feeding that moisture, the problem never really leaves.
A small dish of salt in your car acts like a quiet sponge. It does not wring itself out. It just sits there and drinks. Less water in the air means less fog on the glass. It can also slow the damp that helps mold and musty odors grow in fabric.
Table salt works. Coarse salt or rock salt often works better because the grains have more surface area. You do not need a special brand. You need a container that will not tip when you brake.
How to put salt in your car without making a mess
Do not dump loose salt on the dash. Spills scratch. Wet salt can also be unkind to metal and electronics if it sits in a puddle.
