Tow/Haul on Truck

A long tow/haul story . Several weeks ago in my Ram I picked up a 24 foot cargo trailer to deliver to Daytona from Quitman Ga , maybe 275 miles . My buddy in almost the same truck picked up almost same trailer . When we filled up with fuel in Deland Fl my buddy used 4 more gallons of fuel than i did . The only thing that we did different was that he always runs tow/haul , he sez that all the towing forums say that is the way to go ! I say baloney ,when you are running at legal speed limits in FLAT country you probably do not need to use tow;haul .Your truck will tell you when it is time to turn tow/haul on . If your transmixer is searching , shifting back and forth , thats the time to turn it on !!
Most of my trailer spotting is on the coasts of Ga , Fl , and Alibammi , ain't no hills !