15.6 over the lifetime of the truck is what the dash says, overall. I have a 2015 double cab with the 5.7 and have 52k miles on it. I do feel like I do better on average, but I spend 9 months out of the year towing my boat. I generally fill up at 340 miles on the tank. Thats usually 21 gallons. So thats a little better than 16. Most of my driving is in town. I’ve gotten up to 17.5 on the tank if it was all flat freeway.
