At first glance, placing a glass of salt inside a car might seem like one of those strange, old-fashioned habits that doesn’t quite belong in modern life. With all the advanced climate control systems built into vehicles today, it’s easy to assume that something as simple as salt couldn’t possibly make a difference. But more and more drivers are turning to this surprisingly effective trick—and for good reason. Behind its simplicity lies a practical solution to a problem nearly every driver has faced: excess moisture inside the car.

If you’ve ever stepped into your vehicle on a cold or rainy morning and found your windows fogged up, you already know how frustrating—and even dangerous—it can be. That fog isn’t just an inconvenience. It’s the result of humidity trapped inside your car, condensing on the glass when temperatures shift. This reduces visibility, slows you down, and can create unsafe driving conditions if you’re in a hurry. While most people rely on blasting the heater or wiping the glass, those are temporary fixes. The root of the issue is the moisture itself—and that’s where salt comes in.