Scientists have developed a polyurethane coating that repairs scratches when exposed to sunlight. The self-healing coating uses chitosan a substance found in the shells of crabs and shrimp.
It works by combining the chitosan and organic ring-shaped oxetan compounds with polyurethane. When scratched, the oxetan rings are broken, and ultraviolet light from the sun gets to work on the chitosan, which then attaches to the oxetan and forms a new large molecule that closes the scratch. However, it can only be used in the same spot once any closed scratches can not re-heal if scratched again.
When the coat is applied it takes less than half an hour for the scratched paint to correct itself. More testing is needed, but it's thought that a truly scratch proof car is a mere five years away.