ALL MPG QUESTIONS, UNLESS VERY UNIQUE AND SPECIFIC, WILL BE HERE
Damn!Update: Finished a ~2000 mile road trip in our TRD Pro with 4 adults and 2 kids, towing a 6400# trailer (dry weight plus gear estimate and partial tank liquid load). Have a platform roof rack with fuel cans and recovery boards on the roof. Speed was predominantly 60 to 65 mph. One long drive on a country road at 55mph got me up to 10.8 MPG, which was my single tank towing record. Otherwise, fuel economy while towing was nearly always 8.5 to 10 MPG, as confirmed by manual calculation and computer. Interestingly, this included the average of going up and down multiple steep grade mountain passes in Colorado, typically at 65 mph. This engine was a surprising beast going over those passes, even with the fully loaded rig. Tranny cooler did an excellent job, in temps of 87F, never hit a high temp.
On the low end, the exception to this mileage was a few hundred mile stretch coming south from Kansas through Oklahoma, where I hit some nasty 20mph+ headwinds, and my mileage dropped to 6.7 MPG. This leads to me my biggest frustration with the Sequoia on this trip: the fuel tank. I would really have liked another 10 gallons of fuel capacity. I carried 4 on the roof as insurance, but stopping to fill every 2 hours got really silly. However, if this was the price to pay for having a tow vehicle that was able to easily drive up to Yankee Boy Basin and Imogene in western CO, I'll take it.
Hope these data points help.