Mileage

Empty @ 60mph = 20mpg
Towing @ 60mph = 11mpg

2007 Ford F350 diesel pulling or not pulling 5th wheel Jayco 12 to 14 mpg up hill or down Cape Cod to Alaska Cape Cod to Wyoming

I towed last, last October. Total weight was 23,900 Lbs. I got anywhere from 10-12 mpg, depending on terrain and wind. TV is a 2011 GMC, 1 ton dually, crew cab, long box, 4x4, Duramax. 5er is a a 2009, 35 ft, Silverback. We were packed for 12 days of dry camping with 122 gallons of water, 15 gallons of gasoline for the genny and all the other necessities needed. My 2001, GMC, crew cab, short box, 4x4, 3/4 ton Duramax got better mpg towing the same 5er but weighed less and had less horse power.

'03 2500 Dodge/Cummins 305/555 HO with the NV5600 6 speed manual 3.73 axle pulling a 11200 lb very flat nose/square corner '97 5th wheel trailer.
Empty truck on the highway averages 21-23 mpg depending......
Don't have a city out here as were all rural...
Pulling the 11200 lb 5er averages 12-12.5 mpg all pencil figures

'06 F-350 stock w/coolant filter dually & '10 Montana 3665RE (15.6k max)w/LT tires:
Highway not towing - 17-18 mpg
City not towing - 14-16 mpg
Highway towing - 11- 13 mpg
City towing - 10-11 mpg

Don't know,don't care.

75 MPG Down hill only

Bad and worse.

2001 dodge 2500 auto 3.54 Pulling 27sl Alpenlite combined weight 17800. 12.5 at 60 average 12000 miles to Alaska. 17.5 to 18 empty average.

2003 F350 152,000 miles.
30 ft 5er 9600 lbs
Hwy empty 16-17 empty
Around town 14-15
Towing 9-10.5
Completely stock