“self-healing, urethane-based film

Urethane? You mean paint?

https://www.eastwood.com/paints/automotive-finishes/colors/single-stage-urethane.html

Its like these amateurs are figuring out why we paint cars... its because Urethane protects the metals from rust. I guess they could use Urethane film instead, but that's probably just not as good or efficient as paint...