Your car windows are not sunscreen.

Yes.

Glass blocks UVB rays (the ones that cause immediate sunburn) but lets UVA rays through. UVA rays cause skin aging and can contribute to skin cancer over time. If you’re driving for more than a few minutes, especially midday, your left arm and the side of your face are getting a steady dose.

The damage is cumulative. That tan line on the driver’s side isn’t a badge of honor.

Slap on some SPF 30+ on exposed skin before you start the engine. Or get UV-blocking window film and still be lazy. Your choice.