My Diesel Mileage Sucks

Themistocles

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Took my first hwy. trip after getting it back from the dealership. I got 27.1 on a California freeway with the cruise set on 70. I was on surface roads for about 20 of 120 miles. Does this seem about right with you all? Around town on startups from a light the gage goes down to about 5mpg until I get it rolling, then as the speed increases and I let up on the pedal, it goes up to about 20. What do you think? Do I have a continuing complaint or did the dealership get it right? Thanks for your opinions.
Hwy is about what I was getting on 33s...around town is maybe a touch low...but that really depends. When I am driving around DC that is about where I am at. When I am out in towns with a few more/longer open stretches between lights I might see 21 - 23 for a short time. However, to me it sounds like they fixed the problem.
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Kevin Mojito

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I know, not a 3.0 JL. I have a old 7.3 powerstroke. It changes a pretty good swing with air temp and winter to summer blend fuel. As low as 14 and as high as 22, unloaded.
 
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LeodaJeep

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With highway only use I am now getting 25.8. I think that might be low?
 

Alex01

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We are getting around 24 mpg on the highway, fairly flat, going around 75 mph - stock lift/tires. Considering my ram 2500 gets 22 that isn't amazing but compared to my TJ that gets about 12 mpg it's incredible. I dont expect much out of a vehicle that's shaped like a brick.
 
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LeodaJeep

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We are getting around 24 mpg on the highway, fairly flat, going around 75 mph - stock lift/tires. Considering my ram 2500 gets 22 that isn't amazing but compared to my TJ that gets about 12 mpg it's incredible. I dont expect much out of a vehicle that's shaped like a brick.
I get the brick thing, But I traded in my 2.0 to improve my mileage. If I had it to do over again I wouldn’t. On the highway I was expecting maybe 28 and some in here so they get 30+
 

Alex01

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I get the brick thing, But I traded in my 2.0 to improve my mileage. If I had it to do over again I wouldn’t. On the highway I was expecting maybe 28 and some in here so they get 30+
I would bet the people reporting mileage like that have non rubicons which are lower and have highway tires.

I'm really hoping that the diesel will shine once a taller lift and bigger tires are installed. My thought was the torque of the diesel would mitigate some of the hit to MPG when moving up.

Another pro though is that the diesel shouldn't be working as hard to maintain speeds than the 2.0 and over a long period I'd expect it to last longer.

I do however understand the frustration in thinking something will get more mpg than it is. That was the case for my wives former Honda CRV and Odyssey. Both were under the posted city mpg in the real world which drove me insane.
 
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Heimkehr

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I do however understand the frustration in thinking something will get more mpg than it is. That was the case for my wives former Honda CRV and Odyssey. Both were under the posted city mpg in the real world which drove me insane.
We've two CR-Vs in the garage.

Wife drives a 2019 1.5T. She's a good driver, and the engine regularly exceeds the window sticker's City and Hwy fuel mileage figures...not by a lot, but consistently enough to impress. Fair credit must be shared with the CVT; Honda did a remarkable job tuning that transmission with a perfect blend of economy and performance. This is very similar to my thoughts regarding the 850RE that is paired with my JLU's 2.0T.

Offspring drives a 2010 2.4L NA that meets the sticker's fuel mileage figures if driven with a bit more care, a bit more intent, than is required with the 2019. The mpg display is less dynamic than the one in the 2019; perhaps that's something to do with it. Said differently, it has a slower refresh rate than the newer vehicle, and more mileage has to accumulate to observe the anticipated increase in fuel efficiency when it's expected to occur.
 
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LeodaJeep

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We've two CR-Vs in the garage.

Wife drives a 2019 1.5T. She's a good driver, and the engine regularly exceeds the window sticker's City and Hwy fuel mileage figures...not by a lot, but consistently enough to impress. Fair credit must be shared with the CVT; Honda did a remarkable job tuning that transmission with a perfect blend of economy and performance. This is very similar to my thoughts regarding the 850RE that is paired with my JLU's 2.0T.

Offspring drives a 2010 2.4L NA that meets the sticker's fuel mileage figures if driven with a bit more care, a bit more intent, than is required with the 2019. The mpg display is less dynamic than the one in the 2019; perhaps that's something to do with it. Said differently, it has a slower refresh rate than the newer vehicle, and more mileage has to accumulate to observe the anticipated increase in fuel efficiency when it's expected to occur.
Bragging here: Wife drives a Prius Prime, which is a plug in hybrid. The car goes only 25 miles on electric before it switches to hybrid gas over battery power. She works 3 miles from home so the plugged in battery is used exclusively. Get this...she averages 119mpg in her city/hwy mileage! I love my Jeep but love the wife's car mileage.
 

aldo98229

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EPA says you should be averaging 25 MPG; 23.9 is not that far off.

My guess is in due time you should be getting 25 MPG.

Good luck.
 

KrawlSpace

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Leo,

The best I've ever seen with either of my 2021 EcoD's is 24.6. I have one purely stock at it was one time that I had the 24.6 mpgs. On average though, we see 21-22 mpg. My other one (my avatar photo) is lifted (MOPAR 2.5") with 37's, no regear, steel bumpers and I'm getting 21.7 on average. The highest I've seen on it is 22.8 in its current configuration.

I don't have any actual information for you that would help you with your situation, just giving you some useless information that doesn't really help.

I'd like to ride with those who say they are in the upper 20s so I can figure out what they are doing different and then change my habits and achieve those numbers as well.

Safe Jeepin' for you all.
 

Oldbear

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Not a JL, but my 16 Ram 1500 4x4 EcoD consistently delivers 26+ overall, and has broken 30 on numerous occasions on the Interstate on long trips running 75+. Mine has 73k miles on it. It has also averaged a touch over 16 when pulling a Lance 1995 TT. Your mileage should improve a bit as you pass 10k. Note however that NO modern diesel is going to do well on short runs. My “typical” trip is a touch over 20 miles each way with 14 of those each way on the Slab @75+. If your average trip is 4-5 miles or less you will burn more fuel (and have a lot of regens going on). A couple thoughts(1)a cetane booster (Powerservice grey bottle) or similar will kick your cetane a few points and give a bit of mpg boost (EcoD is a European engine and Euro diesel is a LOT higher cetane than ‘Merican fuel, and (2) check with Green Diesel Engineering to see if they’ve got a tune for your Wrangler. I’ve ran a GDE tune for the past 55k miles. Greatly improved throttle response at low speed and a 2 - 2 1/2 mpg boost over untuned. When mine is de tuned to go to the shop it really has a lot of turbo lag and mpg’s drop. I am not associated with GDE in any way, but they are a class act. Highly recommend,
 
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LeodaJeep

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Not a JL, but my 16 Ram 1500 4x4 EcoD consistently delivers 26+ overall, and has broken 30 on numerous occasions on the Interstate on long trips running 75+. Mine has 73k miles on it. It has also averaged a touch over 16 when pulling a Lance 1995 TT. Your mileage should improve a bit as you pass 10k. Note however that NO modern diesel is going to do well on short runs. My “typical” trip is a touch over 20 miles each way with 14 of those each way on the Slab @75+. If your average trip is 4-5 miles or less you will burn more fuel (and have a lot of regens going on). A couple thoughts(1)a cetane booster (Powerservice grey bottle) or similar will kick your cetane a few points and give a bit of mpg boost (EcoD is a European engine and Euro diesel is a LOT higher cetane than ‘Merican fuel, and (2) check with Green Diesel Engineering to see if they’ve got a tune for your Wrangler. I’ve ran a GDE tune for the past 55k miles. Greatly improved throttle response at low speed and a 2 - 2 1/2 mpg boost over untuned. When mine is de tuned to go to the shop it really has a lot of turbo lag and mpg’s drop. I am not associated with GDE in any way, but they are a class act. Highly recommend,
Tks for that info....and I will check with Green Diesel E.
 

40”JLURD

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If I baby my 3.0D, on the Highway I average less than 23.9 and around town around 18: Stock 33" diameter tires too with 3.73 gears. One of the reasons I traded my 2.0 turbo Wrangler was I thought the mileage would be way better than the 2.0 average I was getting. I do not have a heavy foot either; at 4500 miles I'm still holding out hope for the 10K break-in. As much as I love the Diesel in every other way (except for the price of the oil filter), if I had it to do over again, I would still be in my 2.0...and I really hate to be saying that. One of my selling points to my wife of trading in a 1 year old Wrangler was that the mileage was going to be so much better. I have been honest with her and cross my fingers about the possibility of the break-in boost in MPG. How is everyone else's mileage going? Do you think there is something wrong with mine?
How fast do you drive on the highway? Going over 1900 RPM just kills the mileage…

City mileage blows

I get 15.3 MPG average combined in mine so needless to say I’m quite dissatisfied as well.
 

FinnCustomKnives

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I get the brick thing, But I traded in my 2.0 to improve my mileage. If I had it to do over again I wouldn’t. On the highway I was expecting maybe 28 and some in here so they get 30+
Truly don't mean for this to sound confrontational, but if you bought the diesel for mileage you bought it for the wrong reasons. It will get better fuel economy, of course, but not enough to really matter. However you have 450 lb/ft, +160 over 2.0t, on tap at any moment. THAT is why the diesel makes sense. For those of us that tow, the diesel is so incredibly worth it.
 
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