just finished a 2588 mile trip pulling about 12000 lbs. (5th wheel)DW kept track and here is the low 9.4 and high 11.9-2013 Dodge 3500 4x4 with 6 speed stick-truck did a very good job-I was impressed!...
2003 Dodge 5.9L Diesel manual 5 speed. Tow 55-60MPH, Tow 13.5K 5er. Average towing MPG over 32,000 miles: 11.7. Best was 12.3 and worst was 10.9. Very consistent uphill, downhill, into the wind, with tail wind. I drive conservatively and love my 190K mile Dodge!