Going back to front, I totally agree and have posted numerous times that the reason for buying a ED is not to save money.
Your post said identical trucks except engine and axle ratio. And your sig says you have a Hemi with a 3.21. So, presumably, your ED was a 3.92 rear end.
In my mind, that goes a long way to explaining why your mileage with the ED was so low and your Hemi as high as it is.
My situation is the reverse. According to Fuelly, my current stats are:
Hemi w/3.92 (over 73K miles): 14.1 MPG
ED w/3.21 (over 7,439 miles): 23.3 MPG
Unfortunately, Fuelly doesn't seem to support filtering for what rear end gearing you have. It doesn't even let me filter for EDs from '20 on. But, among all RAM 1500 diesels, it looks like average fuel economy is 22 MPG.
And for all eTorque Hemis, the average is somewhere around 15.7 MPG. Non-eTorque (2011 - 2021) is just a bit lower.
You get a 3 MPG difference. I get 9. The Fuelly averages say 6. I'm guessing that is the difference in rear ends coming into play. You have worst case. I have best case. Fuelly has all cases. I feel pretty good about saying that all things being equal, including rear end gearing, the ED will show about 6 MPG better fuel economy.
Current fuel prices where I am are $4.19 for diesel and $2.91 for gas. Using Fuelly mileage numbers, that yields:
19.0 cents per mile for ED
18.5 cents per mile for Hemi
I think DEF adds ROUGLY 0.4 cents per mile to the ED, so at current fuel prices (and even without counting DEF), the ED actually costs more to drive, without even factoring in the more expensive maintenance.
Of course, that is assuming the same rear ends. I think there is a case to be made for some Hemi owners to have a 3.92. I don't think there is very much case at all for ED owners to have a 3.92. So, if you compare what actually makes sense to buy (i.e. compare Hemi w/3.92 to ED w/3.21), then the ED does have a slight cost advantage (before you factor in maintenance). For ME, using MY #s, I am saving 2.1 cents per mile (1.7 cents after buying DEF). Still not much, and definitely not offsetting maintenance.
As far as noise, I test drove a '22 ED (after driving to the dealer and home after in my '19 Hemi). And then I bought a different one. There is no question (in MY mind, anyway) that the ED is quieter in all conditions. This is speaking from the perspective of the driver, with all windows closed.
They are both inaudible at idle (when fully warm). The ED is quieter when accelerating. The ED is quieter when rolling at a steady speed.
If your ED was not quieter (in the parameters I laid out - fully warm and all windows closed), then I would say there was something wrong. Maybe bad ANC (active noise cancellation) in your truck. I don't know. Even my dad, who rode in my old truck plenty of times, was riding in my new truck and out of the blue commented, "this really IS quiet!"
My brother bought a '20 Hemi that is otherwise almost identical to my '21 ED right before I bought my ED. When I get a chance, I will have to download a sound meter app and try to compare them.
Thanks for this write up. Very well explained. Right now, I have the 2500 6.4 Hemi and you can imagine my fuel mileage. LOL But I need to go to a 1500 now because I see no need for the 3/4 ton now.