Might not mean much to you since mine is older but 2002 Ram 2500 CTD 5.9L 4x4 3.55 gears 4 speed auto OD. 82K miles. Towing Imagine 2950RL @ 9300#
Average MPG towing 10, unloaded 15-16. Since its a 4x4 is gets lower fuel mileage anyway (more gears & axles to turn) than a 4x2. My 3.55 gears will get a little better mileage than the 4.10 ratio. No DEF and minimal emissions compared to the newer Rams. I dont have tow/haul mode just an OD switch. Mostly run in OD unless hilly then lockout OD and run in 3rd gear.
some of the guys with older CTD that chip them and run aftermarket fuel systems are having problems with the lift pump and the injector pump going out.
http://www.thedieselgarage.com/forum...ally-read.html



I suspect you guys with the new Rams in Tow/Haul mode are running in like 4th gear? I would think using the engine brake some or a lot would decrease fuel mileage? I read somewhere on the Cummins forum that the new CTD are not really getting any better fuel mileage than the older ones because of the DEF and emissions and they are injecting more fuel into the engine during regen to help it run cleaner and keep the exhaust system free of blockage. Don't know if thats true or not.