I try to go shopping for new things for the store about once a week, most of the time it happens on Mondays. You never know what you're going to find out there waiting for you, which is the thrill of it all for me. However, in the last six months I've learned there are some things I can't do without in my car.
Everyone underestimates what I can get into my little VW Rabbit! I've actually hauled a five-foot buffet table (with a little room to spare), a large old-fashioned wing back chair and bikes in that trusty car. Occasionally, it's a little tight and it's nice to have my bungee cords when the hatchback can't quite make it all the way closed. They also remind me of my Grandpa for some reason, maybe those old school colors, but I like them :)
This is to protect your car and your purchases! A rug gives a little more padding than a sheet so if you're new love seat has a spring sticking out of the bottom, you won't snag your car interior. You can also add some trendy colors to that boring car felt that plagues the trunk, ha.
This is along the same lines of the rug, but with the bigger surface you can wrap up that old baker's rack so your car won't get covered in dirt and rust. It folds up small so it won't take up space. Plus, you never know when you might end up at the beach without a towel and need something to sunbathe on :)
This is pretty obvious, you need to make sure you'll actually be able to get that vintage desk home once you've bought it. Oh, and my measuring tape is a Cleveland Browns football helmet (thanks, Dad), you can choose whichever NFL team you desire...
I almost always avoid the plastic bags, but when you're out shopping all day you might end up with a used goods explosion in your backseat if you're not careful. I like to keep some kind of box or even a plastic crate in the back to throw my purchases in throughout the day. It keeps the car tidy and protects your bargains in the long run.
One thing not shown is what I like to call the "backseat snack." Sometimes you're gone a lot longer than you originally planned and it's always nice to have that emergency bag of Goldfish hanging out back there :)