Modified Cummins Towing MPG
 

Alright, I'm just looking for a little confirmation on something I already believe I know the ansewer to. I have an aquantance that claims his 5.9 Cummins HO Dually with a number of Mods (which he hasn't disclosed) claims that he can load up his cattle trailer to a weight of 30k lbs (GVWR of probably around 38k), tow at 75 mph, and yield 17 mpg? Personally, I'm not a big diesel person, however I'm fully aware of all of the mods that can be made from lift pumps, to injectors, to turbos, to head studs, and so on. The claim appeared to be completely outlandish and goes against most everything I know however I really don't have any evidence one way or the other short of his claim. Any thoughts. If it's plausible that fine but at the same time most of they guys I know that are towing with diesels modified or not are no where near 38k lbs and get anywhere from 8 mpg to 13 mpg. 17 mpg seems like a bit of a stretch especially with the weight and speed. Any thoughts?

Ya, he is at 8 or so, maybe that 17 is neutral rolling down hill!

I get 15-16 doing 65mph with 20K highway. Stop and go sucks big time

No way. I only get 17.5 pullin my 6500 pound boat at 70

Yeah he's blowing smoke! My dually empty gets 19-21 but pulling on average 20-30k I get from 10-12mpg max

this guy here hit it :tu:

Thanks guys, I was amost certain he was blowin smoke however I always find it hard to pull my foot outa my mouth after the fact. Didn't wanna make a fool of myself.

hes most likey lookin at the fuel mileage thing up on the roof. hell empty it tells me i can get 40mpg. but when i hand it im only gettin about 22-25

I have found that if I reset my overhead when I fuel up it's pretty close, just don't mess with it between fuel ups

I have never used the overhead 'lie-o-meter' but I have a Smarty jr set for towing and I am lucky to get 14 mpg empty but towing my 8.7k toy hauler at 65 mph it gets a consistant 11 mpg towing out west where 6% grades are common, which I'm happy with. I've always wondered when others are saying they get 15 towing their 15k 5ers at 70 mph would I get that if I were driving that same rig? To me it's basically like asking the fisherman how big his catch was. If you chose to believe it that's OK with me.