Hot Rods Your car on an event T-Shirt ?

Our old 51' Merc was used as a Hot August Nights t shirt car (not official merch) and then the same image was reused for shows in Lake Havasu and others in So-Cal that we never even went to. The t-shirt maker would sometimes reverse the image and change the colors but you could always tell it was our car. He told me he sold over 1000 shirts at one show at $20 a piece. Got me thinking and talked to a lawyer buddy who basically said the image belongs to the photographer and described all the color changes an what not makes it his image. Not that I wanted payment but the guy made more money on the shirts than we had in the car! He did give me shirts from the various shows he used it for. Years later he said he lost all his artwork in a fire and had to start from scratch again.