Fuels and such, but also the speeds weren't the same back then. 55-60mph cruise. Now 70+. They weren't built to handle sustained speeds like now. Also, much more congestion on roads, add in 1000's in parade ish conditions - troubles. Also, many people don't test their systems. Oh it works great in town on cruise night - lets drive 1000 miles in 1000's of cars in stop and go traffic at best. The Power Tour is creating the perfect storm. I remember reading one time about Dream Cruise. It was said to pull your front bumper up tight against a brick wall, let it idle at 90° for an hour. If it doesn't overheat, you may be ok.