We have a bone stock RWD '02 with XL-Rated AT tires, run the same tires on my truck, even with the same tires...it is a road couch compared to my Tacoma. While I use the Taco more... have commuted in the "Pooper" from time to time. Commute is 60 miles round trip, average 20 mpg with the cruise set at 65mph. No stop and go traffic, as I can schedule my day to miss the arsejackery.
Have read the 4WD's get roughly 15 mpg.