Aqua blox for water.
Mainstay food cookie rations for food.

Both tout a "5 year shelf life" so I would expect them to last maybe 3 years in a car
before I'd even begin to worry.

You could also get a Scepter Runt 2.5 gallon water can.
Tough enough for our military.

The mainstay cookie rations taste pretty darn good too.