"That's certainly good advice for normal circumstances but conditions where they were are much more extreme and suited more to a winter expedition special forces unit or similar."
I live in San Diego, every year or two, there is an event that keeps people stuck on the freeway for hours, so I keep enough water for me and to help mothers in other vehicles that have thirsty children.
In case of a terrorist event that locks up the roads to the point where the vehicles have to be abandoned, I keep a go bag, so that I can hike up to thirty miles to my home if I have to, since we are in a desert climate (inland county) I keep a Sunblock Gustbuster umbrella to use during a summer hike, and a reflective tarp to put over the car, if I have to stay with it for a hot afternoon.
The storage bag that people keep their gear in, in their vehicles should always be a large backpack or a large bag with shoulder, carrying straps.
If you have to leave the vehicle, you want to be able to comfortably carry your stuff with you, or if have to go for gas, it is easier to carry the gas can in a backpack than in your hand.
I've started carrying our small bottles of water in our car instead of in my house. There have been enough times when we are really thirsty, and it is very nice to be able to go to the trunk and get some water.
ping