After further investigation, it seems that the most important factor when storing an emergency flashlight in your car is the battery. Ideally, you want a battery that...
can deal both with extreme cold and heat
has a very long shelf life
can't leak or explode
And by far the best option to tick all these boxes seem to be non-reusable AA lithium batteries (not to be confused with alkaline or rechargeable lithium-ion batteries). So what you want is a flashlight that can run off AA batteries and has a mechanical power button to prevent parasitic drain.
With all that in mind, I went with an Acebeam Pokelit AA. Let's see how it treats me.
Thank your for reading my blog post.
@wakarimasen
I thought, that the best are shaking-rechargable flashlights
ひげ
@wakarimasen @LukeAlmighty the ones that are crank powered can be pretty useful in a pinch, it would be good to have one in case you don't have batteries. But a normal flashlight is much better lol, not too mention quiet. Headlamps are even better.
@LukeAlmighty I think those are just a gimmick and don't work all that well when you really need them.