My wife used to have a Thirty-One bag with all the **** in it, in the Cav. She doesn't keep anything in her trunk in the Cruze, and I have the battery jump box held to the back of the trunk in the Cav by the cargo net, so it doesn't try to run into my sub box.
Nothing goes in the trunk of my Cobalt, due to the sub box (I don't have grilles on them, like I do in the Cruze).
Camaro has the jack, spare and T-Top bag. I need to figure out a way to mount the jack to the car, since the factory mount under the rear deck is gone, due to it having a full-custom rear deck.