Japanese automaker Nissan has been using Nissan Scratch Shield technology on their cars for four years now. They've been working on the self-mending coating for three years longer. The way Nissan Scratch Shield works is essentially by preventing scratches, repairing fine scratches, and offering better grip, which will be better realized on an iPhone than a car, for sure. We know; it sounds like a came straight out of a Science Fiction movie. But…