I've got a '17 XD PR gasser and can't ever seem to better than 12.7 mpg unloaded. We bought this truck to tow an 8000 lb travel trailer. Haven't done much trailer towing yet, but I've only seen like 6 mpg on the short hauls we've made with it so far.:surprise: Is this the best I can expect from this truck? We're planning a long distance tow and with a 26 gallon tank at 6 mpg we'll need to stop for gas every 150 miles. WTF? My '05 Chevy Suburban gasser with the 5.3 was getting 18 unloaded and 9-10 when towing and had a 31 gallon tank.