My 2013 Volt has developed an elusive rattle that sounds sort of like it's coming from the right rear upper area of the car, such as where the struts are that help hold the rear hatch up (I had these replaced as part of the recall). My dealer was unable to locate the cause. The struts seem solidly attached. We thought perhaps the noise was coming from some metalwork on the hatch itself, and they tightened a bolt and did something with "lock tight", but that, apparently, was not the reason for the rattle, because it's still there. It's not major, but it's pretty regular when going over minor road bumps, and it's irritating. Anybody else notice this sound coming from the upper rear part of the car?