My 04.5 is a 2WD long bed Quad cab. I average between 18 and 23 solo. I make the same trip every year towing 2500 mile round trip to Fl and back to Jersey. Last years trip was 14.8 southbound and 16.8 return trip. I attribute the difference to two factors ..... #1 I am not in a hurry to get back to work on the return trip.
.... #2 I go south the end of March (still selling a winter blend of fuel) and come home the end of April. (back to summer blend)
My truck is stock and I think the 06 and the 04.5 high out-put 5.9 are very similar if not the same. IMHO you will not find a truck with better mpg towing than the 5.9 HO engine. My 94 got 26 highway but dropped to 12.5 to 14 towing. Sorry for being long-winded, Hank
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http://www.turbodieselregister.com/ .... Is a great site to get all the info you need on Ram-Cummins trucks.
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Hank & Lynn
2007 Cougar 290RKS, E-Z Flex, 16" XPS RIBs ( SOLD
.. Gonna miss her ... looking for new 5r)
2004.5 Dodge 2500 QC, LB, 5.9HO, WestTach gauges, Ride-Rite