Yes, your comment about a book is a good idea.
As for a radio, I would say you can turn on the car radio from time to time, especially at news time.
This should not drain your car battery.
AFAIK, when a great number of people have got stuck on snowbound highways, nobody died. "Gendarmes" (policemen) or firemen were (more or less) reachable and if real death risk existed, an (air ?) evacuation was certainly possible, for that person. But there was no way ALL the trapped people could be evacuated.
I guess it's more life threatening, if your are the only trapped car, on a little road somewhere in the snow ... because then nobody knows it and you really are alone ...
In either case, if you have to spend the whole - very cold - night in a car, alone or with wife and child, if you can have some warm beverage, that is more than nice...
could be a life saver.
I sometimes use that emergency stove in my car to warm water and add instant dehydrated soup... I just ensure a window is partly open and I place the stove on a metal plate (side cover of micro-computer).
The kit may also have a dual purpose and be removed from trunk to go in the backpack.
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Alain