My usual city mileage is 12-13mpg...
I live in the downtown of a very heavy traffic city and I do very short trips...
My KJ has a roof mount for a tandem bicycle (soon it will have a kayak mount for a tandem kayak

), has the skid plate group and I always carry my 48'' farm jack under the back seat and the whole recovery kit (tow straps, shackles, etc. ), a twin-piston heavy duty air compressor, a fire extinguisher, a first aid kit and a lot of other stuff...
Since I have a 42RLE (1st isn't low enough I think), I really want a 4.10 regear... I'm seriously thinking in getting a 8000lbs winch and a rear hitch... so go figure...
The good side is my current highway economy... never less than 21mpg when the road is flat... if it becomes hilly (like the highway to the beach) then I get 18-19mpg... I travel in low traffic hours so i can put the cruise control on 55-65mph depending on the traffic conditions and relax

I wonder if its related to the 42RLE high O/D...