Should I buy one or build one of my own emergency car kits?

You can purchase car kits from several companies.  The most important thing that you need to do is make sure you tailor your car kit to your environment.  I live where we get lots of snowfall each year.  I pay special attention to making sure that warmth is a high priority along with being visible.

You will want a car kit for each of your vehicles.  It needs to be small enough that it can fit under a seat or in the trunk not taking up too much space.  Make sure to never take it out to fit more stuff in your trunk.