Review on 🔇 S'mart Mat - RED 150 Mil 20 Sqft Car Sound Deadener Material - Audio Noise Insulation Reduction & Foamed Small-Meshed Polyethylene Heat-Insulation with Strong Adhesion by Art Porras

To add to the rest, it's incredibly sticky and super easy to apply. I've installed it in the rear hatch (Hyundai Kona), along the rear fenders, tailgate and in all 4 doors. It didn't make it super quiet like a luxury car, but it was noticeable. I had a colleague who drove with me (didn't know what type of work I was doing) and they commented on how quiet it was. I personally didn't find it that quiet as I had really forgotten how loud it was. But in the end I'm very happy with the results, especially considering the overall cost and effort. Also, the doors "get heavier/harder" when closed - a really useful HIT bonus I suppose!