One of the original composites applications in the automotive industry was removable roofs on Chevrolet/GMC K10 Blazers in the 68-72 years, which continued on the Blazers until about 1991.  The one-piece composite roofs were durable and relatively lightweight, and way too complicated to be made of steel.  Their resistance to rust has left us in the northern states with only the tops left to the Blazer.blazer-roofThis composite part has some mold and mildew on it, but is still mostly as structurally sound as the day it was manufactured.  It still has the side windows installed and has clearly sunk down into the grass and dirt, but I am sure it could be lifted out and sanded and painted and re-installed on a vehicle.  Good as new!