I have to agree with Davel1971, I have a F350 Dually with 6.0
International engine and get 12mph if not more and run around
375 up to 390 miles to a tank of fuel while towing my Chappy.
It's all in how you drive, if you keep your foot in it all the time
of course you will get lower mileage, I drive around 62 to 64mph
and see lots of hot rods passing me with there trailers.
2006 Coachmen Chaparral 277DS
Coachmen Owners Association
2005 Ford F350 Dually
Last years Camping 72 days
This years Camping 65 days Ugh