dan,
try getting a good-sized screwdriver, and pushing down hard on the discs and then tightening them. you should feel the screw "bite" and get tight, and then they will stay in place, even when you remove the mats for cleaning. anyway, that was my experience.
the only annoyance i have so far is some noise coming from the trunk area or rear deck when i'm on slighly rough roads. it sounds sort of like a briefcase bouncing around. i think it might be all the goofy panels on the floor of the trunk, or maybe the headrest for the right rear back seat. the dealer tried putting padding around the straps for the gas tank, but that was not the source of the noise. probably the worst thing about this wonderful machine is not being able to drive it fast without anxiety. i've already had two tickets, and one is going to cost me $750. i love the car, and i recommend the dinan software; much better throttle response in both modes.
michael