Previous owner "upgraded" the tires to 265/70R15s which work great in the snow, but I'm pretty sure they're what's keeping me from even getting the EPA rated mileage. Currently have only filled up twice and both were around 14.5mpg, but it's been miserable cold and I it barely gets warmed up on my short drive.
Current Mods:
Tire pressure is about 50% above suggested max. (52 with a max 35). 200 watt oil pan warmer. Some grill blocks, working on all of them.
Planned Mods:
More grill blocks and a belly pan. Fluid swap with full synthetic oil, trans, and possibly diff and transfer case. Engine block heater. Definitely some areo around the tires, but I'm not sure how yet. Add engine switch, and go sans alternator and fan. Add a bed cap of some sort.