I most often use the truck for towing the 5th wheel. My best highway runs to Portland and back were in the mid-24s, but I have the 3.42 gear set also. typical mixed use commute is in the ~19s, mixed meaning stop and go for part of it in Seattle
Towing the trailer MPG is very much trip dependent. Mountains are going to get me 12, a run down I-5, 15-ish.
My DD is still the beetle in the mid 40s combined with the train and my bike.
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2007 Dodge Ram 3500 SRW 4x4 with 6MT
2003 TDI Beetle
2002 TDI Beetle
currently parked - 1996 Dodge 2500 Cummins Turbodiesel
Custom cab, auto, 3.55 gears