This may help or may not. I have a 16K fifth wheel with a 3700 lb pin weight. Pulling on flats I’ll get 12-14 mpg. Unloaded at 75 mph I’ll get 22-24mpg. IMO unless you tow heavy, tow often over 7K, or put a lot of highway miles on your truck AND tow over 7K, get the 6.4. Diesel option cost too...