We have a much smaller trailer, and tow with a F150 SC 3.5 l twin turbo, that replaced a Toyota Tundra with the 5.7 V8. The Tundra would average 9.5, to 10.5, depending on the wind and hills. The F150 has averaged a little over 12 mpg on the last three trips, and pulls much better. Unhook the trailer, and it almost doubles.
We never tow with the cruise on, and always use the tow/haul mode.
Every day's a learning experience, though sometimes not what we expected.
2012 Jay Flight 19RD
2016 Ford F150 XLT 2X4 SC 3.5L Eco Max Tow
2010 Tundra TRD DBL Cab (Traded)
1 Spoiled Dog