We have a '13 HEMI Citadel and my wife kept telling me there's a "buzzing" in the dash at certain speeds. After fiddling around trying everything I could to make it buzz....I drove it and figured it was coming from the driver's side left leg area like you guys are describing. I determined that it is the parking brake mechanism that's vibrating at certain times on rough roads or bridges.
I complained to the dealer and they tightened the nuts....this made it worse. I think maybe a little spray grease in the mechanism may quiet it down, but haven't tried it yet.
BTW ours currently has 28,000 miles.
It previously had a terrible rattle in the headliner behind the driver's head....especially when you would shut the doors. It turned out it was the roof support bracket bolts were not tightened down and the whole bracket was flexing and rattling. I don't blame this on the factory, however...as the dealer had to fix a sunroof issue and messed up all kinds of things in the headliner...including the headliner itself. They had to replace that at about $2,000 total.
Needless to say, after a big fiasco of the dealer screwing up a number of things....I'll never go back to them and filed about 7 complaints against them with Chrysler Corporate.