9-12 towing 8K-10.5K
12-14 short trip/lots of idling
15-16 city
20 hwy
My last trip, (490 miles/24 gallons) I got 20.4 mpg.
No, really, it really does. No Lie-O-Meter™ on an XL. Mileage is about 6-8 mpg worse when my wife fills it up with diesel.

It's a 2003 traditional cab (my Korean neighbor calls it that. It's flied lice, you plick.), 2wd, 5.4L gas V8, 3.73 and 6-speed manual. It's not much, but we like it.