Took the 2003 3500 out for the first ride with our 25ft Airstream. Huntsville, AL to Mtn Home, AR via Jonesboro. While the truck exhibits better milage than my '99 CTD without the trailer (21+), the milage with the trailer seems to be the same or a little lower... even though I'm towing at a slightly lower speed (60 vs 65+) and I've gone from an automatic to a 6 spd. And here's the crazy part... I seem to get better milage when I'm in the hills driving in 5th at 50 mph (16-17mpg) vs driving in 6th on the flat at 60 mph (14-15 mpg).

Am I smoking the wrong brand of cigarettes, or could there be that much difference in diesel fuels???

Confused Engineer.........

 

look at your rpms and see where your at at those speeds the sweet spot seems to be around 2k

 

50 to 60 is actually quite a jump. A lot of wind resistance develops. I know the on board computer is unreliable, but mine shows about 1 MPG drop for every 2-3 MPH at those speeds on level ground and constant speed.

Cya