In the one evacuation I have been in government automobile fuel economy ratings were completely irrelevant since I spent the time parked on a freeway with a million of my closest friends. The accelerator pedal was largely unused; most acceleration was accomplished by easing off the brake. I was in 1st gear 90%+ of the trip.

I doubt the vehicle makes much difference, other than to be sure you can stay warm and dry even in stop-and-go traffic. Planning is the key - where will you go? What will traffic be like if *everyone in town* evacuates at the same time? Which destinations are realistic based on your departure point (might depend on departure from work or departure from home)? What items will you need between departure and final arrival?

My personal and "precinct" evacuation plans just have me driving the usual route 30 miles to my parent's house. My "urban" evacuation plan - where the entire city has to leave - is more elaborate due to the desire to avoid routes others might use: it's probably more realistic to hope to refuel in Tumble Weed, West Texas than to try the shorter I-35 direct route between Austin, TX and Dallas.

In the "urban" scenario I'd also grab a sleeping bag, case of bottled water, and a bag of food, as sell as the toolbox if it wasn't in the car already.