Reviving this topic, especially interested in the viability of lithium batteries in the summer heat of a parked car. It looks like there are mixed opinions about that in this thread and two other similar ones:
I prefer something quite bright (~750 lumens or more) and I don’t even mind blinky modes (preferably hidden) for emergency signaling. There are some 4xAA lights that fit the bill, but for the convenience of keeping it charged it would be ideal if it had integrated USB charging, and I don’t know of any non-lithium battery lights with that feature.