In the later 1960s, after the vinyl roof option was very popular, there was a spray-on simulated vinyl roof that I believe was even an option on Dodge pickups. Kind of looked like rough asphalt, not quite like the glued-on factory equipment vinyl fabric. There were even kits in J.C. Whitney!
In the 1980s, there was a barrier coating that was first applied to 1981 Chevy Citations on the lower portions of two-tone cars. It was a rock chip coating that was painted over. Kind of flexible, but not much.