I discovered, quite by accident, that the right roll hoop, while fixed in place and will not leave, rattles around the 3,000 mark near when the torque is at its highest and the engine is relatively slow. I have had the luggage rack installed and keep an umbrella snugged to the hoops and the rack with a bungee tie down. That damped the racket so when I removed the umbrella and finally the luggage rack the rattle was loud. The hoop is bolted in place but it is not necessarily a tight fit so there is movement. Remove the boot tray and access is there. Remove the hoop and squeeze in some silicone caulk then replace the hoop should fix the problem.
I am always amazed at just how much this car is a kludge...
