Safety: avoid thermal shocks that could crack the glass.
Speed: the system acts in just a few seconds.
Effectiveness: prevents fogging during the journey.
Some tips for optimal defrosting
Turn on the air conditioning: even in winter, it helps reduce humidity.
Keep your windows clean: dirty windows keep fogging up.
Always stay nearby: leaving the engine running unattended can be risky, or even prohibited in some cases.
The alternative for older cars
If your car does not have a demisting button, you can opt for other effective solutions:
Use a commercially available defrosting spray.
Protect the windshield with an anti-frost tarp placed the day before.
Make a homemade solution (mixture of water and isopropyl alcohol) to spray on the frost.
