I've lived in the northland for a while and my car generally has an emergency kit that includes some survival stuff. Getting stuck in your car in a blizzard is no damn fun. My Dad always kept $40 hidden in the car, but that was more a "need to pay for gas because these damn cards...." thing.

I would suggest against the suitcase in the trunk more for social reasons[1]. Hidden compartments are illegal in some states[2].

1) it is a sign of cheating

2) drug laws, go figure