FWIW, I get around 13 towing my Starcraft 10/RT (not the most aerodynamic of pop-ups, and not the lightest of right feet when I'm going to Moab) at ~70mph. I get around 14mpg in mixed winter driving, mostly city. Around 17 at moderate highway speeds. Roof rack used to cost me ~2mpg.

OH:
Perhaps it is the mid-80s 5.29 35x12.50 4Runner wrapped around that wonderful 5VZ-FE? Uh... could be...
All you fellers are getting great mileage. Look at the incremental cost of mileage improvement. How much per tank are you saving? Yeah, an O2 sensor R&R at 60K will save you money, and yeah, the payback is getting shorter, but... you see what I mean. Total ROI.
MPG comparos are a little like relative measurement of third members.
And I am not talking driveline.

No need to break out the machine guns.
BTW, the feller who fueled up in Da Junk and got x MPG to Cisco, UT... I'd like to know where in Cisco you fueled up!