I'm running out of bright ideas, so I thought I'd see if the forum had any. This seemed like the most likely sub-forum, since it clearly isn't the others.

My Volt makes a clicking/rattling sound when the right rear corner goes over a bump or dip at speed - doesn't seem to show up if I very slowly go over a curb. It seems to come from somewhere at the rear door or hatch area, either at the center or to the right. I know I could take it to the dealer, but it seems kinda minor to bug them about... Any thoughts?

Maybe related to this?

http://gm-volt.com/forum/showthread.php?9766-New-Interior-Noise

Turned out to be missing/loose pins in the wheel well liner for him.