No VX yet, but...

I keep a soft-sided 6-pack cooler in my Mustang filled with the emergency stuff: jumper cables, flashlight, first aid kit, fix-a-flat, rain gear, gloves, zip ties, screwdriver with interchangeable heads, adjustable wrenches, etc. I've never needed any of it yet since it's a fairly new car, but I've been able to help a couple stranded people out with the jumper cables and gave a guy my first can of fix-a-flat.

On the other side of the trunk is a second cooler (the "Diaper Bag") with a California Duster, rags, towels, detail spray, wax, Windex, paper towels, plastic/tire dressing. Like CobraJet said - never know when you'll find a show (or just need to spruce up a bit. Stupid birds!)

My junk in the trunk tip - stick a strip or two of Velcro ("pointy side") to the stuff you keep in the trunk. It grips the carpet and those items don't roll/bang around as you drive.