Because we use our Volt as a primary car, naturally that involves shopping, etc. The cargo area therefore needed a cargo organizer way to keep things from sloshing around.
I found a collapsible, semi-rigid container at WalMart that is perfect for keeping up to four groceries bags (plus) in place. A restraining bungee cord slipped through some pocket slits in the container. The rubber mat helps keep it from sliding around as well. We like the way the top of the container slopes down to meet the hatch entry lip. The center space is perfect for storing Joe's grocery bags, the side areas for my wife's exercise weights, and the space in front of the container for a yoga mat.
I do wish the cargo area had an additional set of high and low attachment loops midway between the front and back of the cargo space, just forward the side fuse and cubby doors.