I got a good 10 to 10.5 mpg towing my 21 foot boat to the keys last year in 3rd with converter locked up. Mines a 98 2wd 4 door with 155k + on the clock and 3.42 rear. I had the boat loaded with stuff and the truck loaded with stuff. I had to about High 8k to low 9k lbs total truck, boat and gear. Did about 60 to 65 most of the way. I find that if your light on the throttle you get a ton better milage with these things. If I am romping around with it I can almosty watch the gauge go down. May not be as much fun but stop and go really kills the fuel milage on them as well.