So I drummed up some business this past hour for Surefire (or) Fenix and Petzl.
I advised my friend that they should have at least a headlamp (Petzl Zipka) + a flashlight + extra batteries for each light, in each car.
I agree 100%, although I would add that during the winter months you should carry lights that run on lithium batteries. Alkaline & carbon don't hold up too well in the cold.