I've been using Rubbermaid Action Packers. I've been able to fit a lot of tools and car fluids in one as well as flares, emergency triangle and a couple of glow sticks. I plan to get another for food.

The small size is ideal for the back of our van, but I've been able to get most of my gear into the first one so far.

I like the zip tie idea too...I've heard the one in the back of my car sliding around a lot!