I was about 4 cars back behind a guy who had fifteen sheets of 1/4" plywood paneling tied to the roof of his car using that "free rope" that they give away at the big box stores and he had only used a minimum of it. I don't think he had ever hauled anything on the outside of his car before. When the rope broke we were going about 65 mph, and those sheets took off one at a time and in several directions, then began falling like leaves. The other drivers, and me, were dodging these flying sheets and each other while trying to stop as quickly as possible. When it was over, there were eight cars involved, Two cars were off the road, one on the road was facing backwards, and the rest had come to a stop at different angles to the road, but amazingly no one had hit each other or had been hit by any of the plywood. I was about in the middle of all of this. We all helped the guy pick up his paneling and some had some choice words to say to him about his way of tying it all down and then trying to drive at full highway speed with it. He was very apologetic about it, and paid the price because most of his expensive wall paneling had been destroyed beyond use, so I doubt that he ever tried doing that again. It always amazes me how many people have no clue at all when it comes to carrying anything on the outside of their cars, trucks, and trailers, and how poorly they tie it in place.
Central North Carolina