Having grown up in hurricane central (more commonly known as Florida) I can tell you from personal experience that a key factor for an evacuation vehicle is going to be ground clearance. With debris blowing all over the roads, down tree limbs, etc., ground clearance is a very important aspect to take into consideration.

An equally important aspect of an evacuation/survival vehicle is how you outfit it, particularly when it comes to the tires. Very few production vehicles come with TRUE off-road capable tires. I'm amazed at how many people buy these huge 4x4s and then put street tires on them for driving comfort and reduced road noise. I can't tell you how many people I know who have full size, v8 powered, 4 wheel drive trucks and SUVs who THINK they are prepared and ready to drive off road in an emergency when in fact they will be lucky to get 50 feet off of a paved roadway before they get stuck in the wet grass or mud during a storm.

And my last $.02 worth would be a note on making sure it has storage room for extra gas cans (either on top or inside) because gas is worth its weight in gold during a true evacuation.