Stock. Have seen 18mpg unloaded for a trip, but I'm guessing I had a tail wind. My short drive into work every day, 5 miles with stop lights and stop signs, I get 13.5. Until it regens.

yeah that stop and go hurts me pretty good. Ready for a few long hauls to see what i can get. Just put Diesel Kleen (sp?) in my most recent tank. Sure runs more smoothly

not towing with the ac off, driving mostly at night I got 22 on a trip to Tenn in July. Coming back daytime with the ac on it fell to 17 on a Titan V 8 crew cab. Mostly interstate driving at 75+.

towing around town much less

13' Sierra 1500 with the 5.3

I get:
17.5 highway no boat
12 highway with 20 foot boat in tow.

'15 Ford 150 Lariat 5.0 4x4. I get 16 towing a 20' Skeeter. 18.2 highway without towing.

If you really think you're gonna get 20 mpg out of a crew cab 4x4 you're dreaming unless you get the ecodiesel which is hard to find for under $30k. I'm in an 05 crew cab 5.4 Ford, 15-17 highway. Dad has a 2011 ecoboost, he gets 18 highway.

Just got my 2005 Ford F-150, crew cab, 4x4, on 6 inches of lift and 35s. 5.4 Triton. Getting about 16 avg right now, babying it, which is much better than I was expecting. It'll get thirsty if I don't go easy though. On the other hand, my dad has a 2015 F-150 with the 2.7 twin turbo ecoboost, stock. It makes the same torque and more horsepower than my 5.4 does which is crazy. It's much faster cause its turboed. And it flat out pulls great. I towed my 19 foot tandem axle Cajun with it on a longer trip, and not only was I impressed with the motor, but it just handled and felt great on the suspension too. I believe he gets over 20 mpg avg, I think right around 22 on the highway. Oh, and its 4x4 and crew cab. Couldn't recommend looking at one of those enough. Also don't have any experience with the ecodiesel, but haven't heard a bad thing about them either.

2013 F150 5.0 17.5 mpg to work and back and about 16 mpg pulling my 20' ProGator on tandem trailer.