We test drove the early production 2013 RAM 3500 DRW and liked it a lot. They are very nice trucks with great capability and power. We were shopping for a pickup that could handle our 2006 Artic Fox (purchased used) and the way this early 2013 RAM was optioned, it had inadequate payload capability for the camper. We ended up with a 2013 F350 DRW 4X4 CrewCab Camper Package that had plenty of margin on the 4600 lb. payload requirement (I still had to have custom overloads made to get the ride height level - worth every penny). The RAM was otherwise my first choice.
While they are not the same truck, I have discovered the following:
My mileage has improved from 15 unloaded (60 on the level) new to almost 19 in the same conditions with just under 18K on it. Seems the engine gets better with age. This includes the effects of an active regen every 300 miles or so which consumes about 1 quart of diesel to heat the oxygen in the exhaust stream and thereby burn off the accumulated particulate matter (soot). Using cruise control provides the best possible mileage. We get around 12 with camper on, unless it's windy when I've seen single digit numbers.
We've done a lot of research on clean diesels (forgive me for I am a rocket scientist, now retired except for the occasional consulting work) and have turned that research in a small company that we're trying to get off the ground in our retirement, just for fun and entertainment. We are a supporter of the IRV2 forum, and enjoy trying to provide answers to RVer's questions.
Check out our other posts on the subject of DEF, EGR, DPF, and clean diesels for all the details, but here are some things to consider:
The SCR system on all the new diesels (which consume DEF) allow much more efficient combustion (less EGR, higher combustion pressures, MORE BOOST) so in principle they should consume less fuel.
Diesel Particulate Filters DPF have little effect on back pressure, based on seeing the insides of several at the 2013 Diesel Emissions Conference. Turbochargers fully expand the exhaust gas on diesels, resulting in very low static pressures in the exhaust. DPFs are continually improving, and the recent addition of catalysts to make passive regen more effective will use even less diesel to aide combustion of carbon particles in the DPF.
I believe the Cummins in your RAM has active regen similar to the Ford. I also believe it is similar to the Ford in that delayed injection of fuel in the cylinder is used to add heat to the exhaust. This can (in unusual circumstances) result in oil dilution due to washdown in a COLD cylinder.
Chev/GMC Duramax may have come up with a better approach: they added a 9th fuel injector after the turbocharger to add fuel and create heat. Of course it another part that can fail...
Interestingly, the primary culprit in DPF long term life is the residual engine lubricating oil in the cylinder that burns with the diesel. The particulate matter from lubricating oil combustion does not burn off well in the DPF, and converts to ash. Using the oil specified in the owner's manual (low ash causing content) can be important to DPF life.
I'm kind of a half full glass kind of person (especially if it a Red Solo cup with a nice beverage in it which reminds me it's time for a refill
) so here is my closing thought on the subject:
The new trucks are INCREDIBLE: quiet, capable, and powerful, easily driven with amazing safety features, and have had 93-98% of the particulate matter and NOx eliminated from the exhaust. Yes, my friend's 2002 7.3 gets better mileage and is just as capable (and he does not need to add DEF). But I'd rather have the 2013.
Thanks for listening, and as always, send questions on clean diesels our way.