Foggy car windows on damp mornings are often caused by excess humidity trapped inside the vehicle, making the glass misty and the interior feel damp or musty.
A simple household trick is to place a bowl or cup of table salt inside the car, as salt is hygroscopic and can absorb moisture from the surrounding air.
Other options mentioned include crumpled newspaper or silica-gel packets, which work on the same basic principle of reducing excess moisture.
Lowering humidity can help keep windows clearer and the interior fresher, while also reducing the damp conditions that can contribute to mold, odors, corrosion, or other moisture-related problems.