Take a look at the newer, high-efficiency diesel engines from Volkswagen and others. Even coupled with low-ratio gears and less slipstreamed form factor of a small 4WD pickup or SUV and you could probably still get much better MPG's than any gasoline powered models. They are not big on HP, but then again, 4-cylinder SUV's like the Jeep Wrangler and Suzuki Samari still make capable off-road vehicles in most conditions you would want to deal with in a survival situation.

I'd love to own a Sportsmobile. But for the same $120k I could get a pretty nice diesel-pusher RV. Not as flexible in an emergency escape situation, but great range and long-term capabilities.

Probably the ultimate survival vehicle is a dual-purpose motorcycle with full luggage options. Good range, decent carrying capability, on/off-road capable, can easily weave around most obstacles. Only room for two, you would have to sleep in tents, and be subjected to cold/rain. But if I had to escape a sudden disaster in my area, probably my only chance at rapid evacuation will be on a bike, as the roads will be hopelessly clogged with other escapees.

Plus they are just fun to ride.