I have had both of my Pierces and my antique fire engine in various movies. I have not had any bad things happen. In fact, I told the movie company what I expected and what they could and couldn’t do, they were happy to work within my framework.
I also know a PAS member here in Canada that has built a very reputable business in this industry and has well over a 1000 movie car. He too would tell you that it is all about "managing expectations on both sides.