And, the most important item is...

It was unusually cold a few days ago, and a local media source was advising the public about how they should prepare before going out in their cars.  They referred to traditional items like ice scrapers and windshield washer fluid, but I was interested to note their stress on one particular piece of equipment as more important than others: a charged cell phone. This makes a lot of sense, so as to be able to summon emergency assistance. On the other hand, it doesn't say much if your goal is self-sufficiency in an emergency.  I don't think most cell phones would work effectively to clear windshields, though they could be useful to obtain weather forecasts.