18 mpg Dodge while towing?

allen8106 wrote:

azdryheat wrote:
Friend claims 18 mpg while towing 35' toy hauler with 2003 Dodge Cummins Diesel with manual transmission. He says he never goes over 55 mph. Is he for real?

I would be surprised if he gets 18 empty. I have a 2013 Duramax and average about 17 empty and I know that 2003 doesn't get as good a mileage as a 2013 just because of fuel mileage improvements in the last 11 years.

Actually, the empty comment is not true. If I drove my 2003 empty at 55, I would get low 20's MPG range. Best tank I ever got with my truck was 24 MPG at that speed.

Towing 17,000 pounds between 65 MPH - 70 MPH would get about 7.5 - 9 MPG.

The 2003 5.9 got some of the best empty MPG of any diesel - if you kept your foot out of it.