I am a new diesel owner. I ordered my Ram 3500 MegaDually Limited :) in March, took delivery mid June. Just turned 3000 mi. 6.7 CTD/Aisin and 3.73's (4x4). On the trip home from SC, where I took delivery, I was getting 19.6 mpg just before I got home. Basically running empty at 60-75 mph. Now most of my distance is less than 10 miles each way. I still get 12/13mpg in town (avg speed on EVIC-23-27 mph) this is due to number of lights and signs with a max limit of 45.
My last truck, which I just sold this week,was a '99 Ford V10 gasser 4x4. She had 113k on the odo. Since all you can get around here is ethanol mix gas, her mileage suffered. From 11 down to 9 in town and 16 down to 13/14 on the hiway. When I went to MT to pick up my 5er, we got 7-12 depending on grade and fuel type. The Ford had 4.30 gears and would pull like crazy, just not very fast up a steep grade. ESPECIALLY, if you didn't have a running start! She had Banks intake and exhaust systems and Trans-Command module (gives you full-time tow/haul), but we were running the A/C and it would cut out constantly at WOT going up steep grades. Trailer was <10k# GW.
With the new transmissions 5-6 speed auto's and higher output from the gassers, it makes it easier to haul bigger loads.
I threw over 1100# of quick Crete and sand in the bed of my new Ram along with the slider hitch and picture frame adapter. It didn't drop the bumper a bit! May need to double up on the weight box for winter traction.:O
I have to say, as nice as my Lariat CC was, I really love my Ram Mega!