I haven't checked while towing for probably a couple of years. I used to track every trip, but it consistently ran in the 10s, with occasional single tank fillls showing upper 9s and low 11s. It seems like we're either running against a headwind or a crosswind. Must be one of Murphy's Laws.
My non-towing driving is infrequent but pretty much the same, four and a half miles with 900' elevation change each way, 19 hwy each way and three or four miles in town. I checked the last tank because I was planning on changing the fuel filter with the upcoming oil change and I wanted to know if there was any change. Got 16.4 and am working on the new tank full. Not expecting much difference.
'11 Eagle 320RLDS
'02 F350 PSD Dually 4WD
DW's Ride, '13 Expedition