Got to go with the new Jeep 4 door Wrangler (rubicon).

http://www.autoblog.com/2007/04/03/jeep-wrangler-gets-high-sets-record/

considering fuel will likely be an issue in any large scale emergency situation, what would be the overall best engine type?


Gasoline

Standard Diesel (which can obviously also use biodiesel)

Diesel modified to use raw vegetable oil, biodiesel, petrodiesel, or combination of all three.



Seems there are benefits of each. The last one seems the most flexible but I haven't read enough to know how reliable it would be.

The majority of smaller cars have small tanks and therefore short ranges, there will always be an exception to any rule, but in general the larger the vehicle the longer the range.
4x4 does fine on ice assuming the driver knows how to drive.

This was with 4 people in it. Getting on I64 in Maryland somewhere between the WV line and Cumberland those steep off ramps resulted in a lot of buzzing and vibrating and we thought we were going to have to get out and push up the ramp.
My mileage doesn't drop in the mountains, but I can stay in OD also.
We made the mistake of buying a minivan a few years ago. There is a steep hill coming down route 7 between Terra Alta and Kingwood in Preston county. By the time we got to the bottom and up the other side in Kingwood I would have to stand both feet on the brakes to get us stopped. Since I had to travel that hill a few times a year I would have to replace the brakes and rotors every year by the end of summer.
One thing I have learned is to never buy a front wheel drive vehicle, they just don't hold up under tough situations.

Problem with any modern Diesel is the filter and injectors need the fuel to be so clean its very hard to get them to run right on anything but standard diesel.

Nah, it just requires some heating and pre-filtering to run SVO. Biodiesel will run just fine if made properly. Most diesel vehicles are actually filled with biodiesel right from the factory.

in my humble opinion a land rover defender 90 would be best and a 110 even better.(bcos you say size wise not too big)
this is the mother of all off roaders and over time with a little cash you can create a vehicle thats totally self sufficient!! as for off roading..these are in iraq,afghanistan,the jungles of borneo,and the amazon.(although certain upgrades are in place in those extreme parts of the world.
there are many 4x4 forums that can keep you too!!

I would think that in an emergency situation, diesel would be easier to come by. There are fewer vehicles using it, so there would be less comptetition. The government would probably give diesel a higher priority since the transportation industry relies on it for the trucks that deliver food and essential goods.

The maine Issue I see now with diesel is the new deisel engines are super picky. The fuel filters in diesel trucks and cars that you or I would buy are filtering down to the micron requiring very clean fuel otherwise the filters fill up quickly.
The big OTR trucks hauling your food to the grocery store don't have to meet as strict emissions requirements yet so they can operate on less clean fuel. I'm seeing the make your own biodiesel fuel deal getting harder all the time as the vehicle systems get more complex.
older Diesels your safe but the buying something new they are becoming a big headache.

So how would a new diesel run if you removed the filter (only in an emergency of course)? Or are these new engines completely reengineered? I haven't really kept up with the technology.