6.4l terrible mpg

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@Dannycameo The reason why your truck is getting less mpg despite altering the load on your truck is because; cold air is more dense than warm and requires more fuel. You will make hp and tq more readily or increase by tune when intake temps are cooler. It has nothing to do with anything else.

Extreme example: I live in GA. We can have an 80-degree day with a - 40-degree night. If I was driving a highly tuned car with a turbo, I would have to run different maps, to starve off knock/detonation. Air is thin during the day and cold and dense at night. Those changes are so vast to a highly tuned car the computer cannot make up the difference with computer adjustments alone. Air intake could be +150-degrees during the day and 40-degrees at night. I would run maps that dumped fuel and added timing during the cold in comparison to summer maps.

The example for most, with summer and winter driving, are normal vehicles will adjust the fuel, but it happens over months, and most don't really notice it. IME, the difference is 2-5 mpg (vehicle dependent) between summer and winter. While normal vehicles won't add timing, they do have to account for the colder denser air of the winter, to not have detonation/knock.
 

Redfour5

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Hello all, I am new to Ram ownership and this forum. I recently bought a 19 power wagon 27000 miles on it with 35s that I do really like but the mpg is appalling. Around town I can get in the mid teens but the average is much lower because anytime you get near the gas pedal it drops to like 6 so it destroys the average. This is all in a totally unloaded vehicle. I drive 20-30 minutes to and from work on open highway. At 70 and up steady state cruising on flat level road it says 10mpg. I’m getting about 270 miles per tank also. My driving is very normal and a good combination of town and highway.
I have been looking for answers on the forums etc and while there is a lot of discussion about the mileage no one seems to have any real answers. I see a lot of people saying they get mid or high teens on the highway, if that is true it’s really concerning. I know this truck has the MDS system but I can’t tell if it’s operating or not. I never hear or feel any change in the way it runs so maybe that is causing the mileage. There is no engine light or anything so seems unlikely there is an issue with that.
Any help or insights will be greatly appreciated.
It's those 35's getting you. I'm at 16 to 17 highway on Montana 80 mph highways with OEM Transforce/18 inch wheels and 3.73's (will be switching when these are toast). I must admit this truck/engine/rear end combo from an MPG standpoint prefers running down the highway at around 75 mph... It does NOT like city driving at all and 12 to 13 is normal.
 

SniperDroid

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It's those 35's getting you. I'm at 16 to 17 highway on Montana 80 mph highways with OEM Transforce/18 inch wheels and 3.73's (will be switching when these are toast). I must admit this truck/engine/rear end combo from an MPG standpoint prefers running down the highway at around 75 mph... It does NOT like city driving at all and 12 to 13 is normal.
Your driving a 5.7 and the thread is about 6.4's .
 

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my 2020 PW definitely has an issue....in a good way. Not to make light of people who are getting crappy mpg but I recently did a 400+ mile road trip on winter roads and did much of the trip in 4H and still got over 14mpg. this was in Montana, Idaho and Washington ie Missoula to Spokane and back to Missoula and anyone following weather knows it was pretty cold.
 

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my 2020 PW definitely has an issue....in a good way. Not to make light of people who are getting crappy mpg but I recently did a 400+ mile road trip on winter roads and did much of the trip in 4H and still got over 14mpg. this was in Montana, Idaho and Washington ie Missoula to Spokane and back to Missoula and anyone following weather knows it was pretty cold.
I get 15 or 16 when I'm not towing... but I got the truck to tow the camper with. Happy with 9 when towing, 'cuz it's a "Tow Vehicle"! Sure I wish I got more, but I knew it would suck when I bought it. Went for appearance, features and POWER, not so much for economy. If I wanted fuel economy I would have bought a 1500 with a tiny little engine that might...
 

smittyd174

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Just for the heck of it slow down to say 60 your mpg will go up alot . When I towed with my 2016 , 3500 with the Cummins going from 65 to 55 made about 3 -4 mpg difference. It takes alot more power for those extra mph . The question is which is more important 10 or 15 minutes of your time by driving 70 or slow down abit and keep some cash in your wallet . Truck , 4:10 gears , big tires and speed not a recipe for mpg . Good luck .
 

JCE

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my 2020 PW definitely has an issue....in a good way. Not to make light of people who are getting crappy mpg but I recently did a 400+ mile road trip on winter roads and did much of the trip in 4H and still got over 14mpg. this was in Montana, Idaho and Washington ie Missoula to Spokane and back to Missoula and anyone following weather knows it was pretty cold.
Cold and some good steep grades and a gnarly sweeping corner on I90 just across the border in to ID. I'd say 14mpg is a good figure considering the weather and elevation.
 
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Cold and some good steep grades and a knarly sweeping corner on I90 just across the border in to ID. I'd say 14mpg is a good figure considering the weather and elevation.
exactly especially when in 4H most of the way. My 6.4L gets uncannily good mpg all the time.
 
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my 2020 PW definitely has an issue....in a good way. Not to make light of people who are getting crappy mpg but I recently did a 400+ mile road trip on winter roads and did much of the trip in 4H and still got over 14mpg. this was in Montana, Idaho and Washington ie Missoula to Spokane and back to Missoula and anyone following weather knows it was pretty cold.

You also went over several mountain passes ( don't recall if its 2 or 3) going each direction, I hope you didn't have to climb the hill on I 90 south towards US Hwy 2..
 

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You also went over several mountain passes ( don't recall if its 2 or 3) going each direction, I hope you didn't have to climb the hill on I 90 south towards US Hwy 2..
two main passes Lookout pass at the montana idaho border and then forth of july pass in id.
 
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JCE

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You also went over several mountain passes ( don't recall if its 2 or 3) going each direction, I hope you didn't have to climb the hill on I 90 south towards US Hwy 2..
That's a gnarly hill.
 

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That's a gnarly hill.
Yes it is, between 1983-1987 I drove up that hill many times, I topped it at around 5-7 mph in a 7 axel truck trailer grossing 100,000 lbs, I saw first hand how the idiot drivers in Spokane forgot how to drive in the first snow every year and why I hated to be any where near that town during the first snow fall too many wreck's
 
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JCE

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Yes it is, between 1983-1987 I drove up that hill many times, I topped it at around 5-7 mph in a 7 axel truck trailer grossing 100,000 lbs, I saw first hand how the idiot drivers in Spokane forgot how to drive in the first snow every year and why I hated to be any where near that town during the first snow fall too many wreck's
Understandable. Good thing we don't have that kind of elevation anywhere but out in west Texas where it doesn't snow a whole lot, because people here can barely drive properly in dry conditions much less in wet or frozen ones. Lol

One of the first things I'm going to do when we move to Idaho is get a second set of wheels for some Nokian winter tires on both the RAM and Lexus GX460.
 

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Yes it is, between 1983-1987 I drove up that hill many times, I topped it at around 5-7 mph in a 7 axel truck trailer grossing 100,000 lbs, I saw first hand how the idiot drivers in Spokane forgot how to drive in the first snow every year and why I hated to be any where near that town during the first snow fall too many wreck's
we were there on dec 20-21 and leaving on I-90 East bound on the 21st I stopped counting the crashes between Spokane and the state line.. many were simple slide offs but several involved multiple vehicles.
 

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we were there on dec 20-21 and leaving on I-90 East bound on the 21st I stopped counting the crashes between Spokane and the state line.. many were simple slide offs but several involved multiple vehicles.

So your saying things have not changed in Spokane and driver are still Stupid lol...
 

Dannycameo

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@Dannycameo The reason why your truck is getting less mpg despite altering the load on your truck is because; cold air is more dense than warm and requires more fuel. You will make hp and tq more readily or increase by tune when intake temps are cooler. It has nothing to do with anything else.

Extreme example: I live in GA. We can have an 80-degree day with a - 40-degree night. If I was driving a highly tuned car with a turbo, I would have to run different maps, to starve off knock/detonation. Air is thin during the day and cold and dense at night. Those changes are so vast to a highly tuned car the computer cannot make up the difference with computer adjustments alone. Air intake could be +150-degrees during the day and 40-degrees at night. I would run maps that dumped fuel and added timing during the cold in comparison to summer maps.

The example for most, with summer and winter driving, are normal vehicles will adjust the fuel, but it happens over months, and most don't really notice it. IME, the difference is 2-5 mpg (vehicle dependent) between summer and winter. While normal vehicles won't add timing, they do have to account for the colder denser air of the winter, to not have detonation/knock.
Good answer, the difference that you're talking about with the cold air of two miles per gallon to 5 mi per gallon would make sense especially when you're getting close to touching 40 below Celsius and 40 below Fahrenheit.
 

Redfour5

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Your driving a 5.7 and the thread is about 6.4's .
I actually have a 2500 6.4 now. I had a 21 Built to serve bought in June 2021 and traded a 15 Outdoorsman with a 5.7 3.92. The BTS with the 5.7 and 3.21 gears wasn't enough to pull my trailer so I felt comfortable with it. I traded it in March 2022 for a Laramie Hemi 2500. The BTS had the 3.21 and although within specs for towing but at the limit of my payload, I occasionally felt like the trailer was driving the truck... The surprise on that one was that the 3.21 gears towed about as well as the 3.92's except the transmission was doing most of the work vs the 3.92. The 3.21's did get decent daily driving mpg (18/19 highway) vs the 15 Outdoorsman.

I was watching the economy and knew the interest rates would be going up, the trade in market was still relatively hot although not as good as mid 2021 when I got the BTS. I got right at 8K over what I owed on the 1500 and a 3.24% interest rate (84 months) and had been watching MSRP going up and thought to myself, now or never and am very happy overall. I did get manual fold mirrors because of the chip shortage but the rest was good. That very same truck built on the Ram site in November 2022 went from 62,600 built in Nov/Dec 2021 to 69,700 in November 2022 and over 70K now to build. So, I'm done buying trucks right now and considering the short time frame for the 1500 to 2500 deals, ended up doing not bad...

And the biggest surprise has been the mileage on the 2500 with the 6.4 Hemi AFTER about 6K miles on the odometer. It is approximately the same MPG towing as the 1500, both the 3.92 geared 1500 and the 3.21 geared one. It is around 1 to 2 MPG worse than the 1500 BTS regular driving...but about the same as the 2015 5.7 3.92 geared Outdoorsman. I am pleasantly surprised... Now, I felt fine doing daily driving with a 1500. The 2500? not so much. It is a beast. Now, the 2021 BTS was never totally broken in imho so that might have affected mpg's I'm thinking. The new 2500 is...
 

Redfour5

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That's a gnarly hill.
I hate that part of the drive from Helena MT. It's bad road going down obviously built early in the Interstate cycle and the people do drive like they never got a license... And it seems like I always hit it when the weather is not the best... That run down there by Post Falls and the rest area gets so packed. I've seen numerous wrecks or the jams from wrecks there... Just crazy and then Cour D Lene (sic) isn't much better and always being worked on over the last few years... Just be patient and hope you don't need gas...
 
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JCE

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I hate that part of the drive from Helena MT. It's bad road going down obviously built early in the Interstate cycle and the people do drive like they never got a license... And it seems like I always hit it when the weather is not the best... That run down there by Post Falls and the rest area gets so packed. I've seen numerous wrecks or the jams from wrecks there... Just crazy and then Cour D Lene (sic) isn't much better and always being worked on over the last few years... Just be patient and hope you don't need gas...
Indeed. Coeur d’Alene can be a mess with how many out of staters that are moving in up there (and driving up the ******* real estate prices out of my current desireable reach).
 
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dhay13

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I actually have a 2500 6.4 now. I had a 21 Built to serve bought in June 2021 and traded a 15 Outdoorsman with a 5.7 3.92. The BTS with the 5.7 and 3.21 gears wasn't enough to pull my trailer so I felt comfortable with it. I traded it in March 2022 for a Laramie Hemi 2500. The BTS had the 3.21 and although within specs for towing but at the limit of my payload, I occasionally felt like the trailer was driving the truck... The surprise on that one was that the 3.21 gears towed about as well as the 3.92's except the transmission was doing most of the work vs the 3.92. The 3.21's did get decent daily driving mpg (18/19 highway) vs the 15 Outdoorsman.

I was watching the economy and knew the interest rates would be going up, the trade in market was still relatively hot although not as good as mid 2021 when I got the BTS. I got right at 8K over what I owed on the 1500 and a 3.24% interest rate (84 months) and had been watching MSRP going up and thought to myself, now or never and am very happy overall. I did get manual fold mirrors because of the chip shortage but the rest was good. That very same truck built on the Ram site in November 2022 went from 62,600 built in Nov/Dec 2021 to 69,700 in November 2022 and over 70K now to build. So, I'm done buying trucks right now and considering the short time frame for the 1500 to 2500 deals, ended up doing not bad...

And the biggest surprise has been the mileage on the 2500 with the 6.4 Hemi AFTER about 6K miles on the odometer. It is approximately the same MPG towing as the 1500, both the 3.92 geared 1500 and the 3.21 geared one. It is around 1 to 2 MPG worse than the 1500 BTS regular driving...but about the same as the 2015 5.7 3.92 geared Outdoorsman. I am pleasantly surprised... Now, I felt fine doing daily driving with a 1500. The 2500? not so much. It is a beast. Now, the 2021 BTS was never totally broken in imho so that might have affected mpg's I'm thinking. The new 2500 is...
I actually got better mileage with my 2018 2500 6.4 4.10's than with my 2013 1500 5.7 3.55's. I towed my sons 2018 Grand Deign 2670MK 200 miles empty brand new off the lot and got 8.38 hand calculated on the trip there and on the trip back filled with his stuff I got 7.34 MPG. With the 2500 I got 8.49 loaded up. Weighed 8100lbs loaded. So loaded up the 1500 got 7.34. The 2500 got 8.49 MPG. All are hand calculated
 
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