2021 Jeep Gladiator Diesel 3.0 horrible MPG

[staying_tuned]

When you say x average during city driving, are you driving primarily in a city? With 37s and a heavy wheel, I could easily imagine low teens if your truck primarily saw city miles.

Editing, just noticed your avatar. Yeah, massive MPG hit on that setup assuming that is your truck. Not only due to the poke drag and weight, but also the aggressive offset forcing your tires to fight themselves to track straight given our limited adjustability.

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[azaustin]

There is a recall affecting some diesel engines that reduced DEF fluid consumption and increased MPG. I don't remember the specifics but there is a thread on it. Definitely seems like you have an issue. I'm assuming you've calibrated for tire size.

I just had the DEF recall done on my 2021 diesel Gladiator Rubicon and noticed a 2-3 mpg increase on my last round-trip to Flagstaff from Lake Havasu. It seems to be getting better mileage around town too. Mileage on the engine could also be a factor as I just turned 11,000 miles on the odometer. I usually calculate mileage from gallons used versus miles driven. When I first got the truck the fuel mileage readout was optimistic by 2-4mpg. Seems to be getting closer now.

 

[caryw5150]

If you aren’t- and I’m sure some will argue this… I run a diesel additive

Hot Shot's Secret Everyday Diesel Treatment 16 Ounce Squeeze Bottle (HSSEDT16ZS) https://a.co/d/0Y1R550

I run 1-2oz of this when I’m at the pump for a fill up.
Helps put a lubrication property back in the fuel for the fuel pump. I usually note a 1-1.5mpg increase on highway tanks.
Nothing else cheap insurance for the fuel pump


Your fuel economy is insanely low…. 18 mpg if flogging would be ok… anything lower and something is off.

Change your fuel fill up location.
Use gas buddy and see what diesel station seems to be used the most.

you do this EVERY fill up?

 

[caryw5150]

When you say x average during city driving, are you driving primarily in a city? With 37s and a heavy wheel, I could easily imagine low teens if your truck primarily saw city miles.

Editing, just noticed your avatar. Yeah, massive MPG hit on that setup assuming that is your truck. Not only due to the poke drag and weight, but also the aggressive offset forcing your tires to fight themselves to track straight given our limited adjustability.

is there anything to be done to help mitigate this then. i'm new to the jeep way..... i'm digging it however yeah wanting to absorb as much info as i can.

 

[caryw5150]

is there anything to be done to help mitigate this then. i'm new to the jeep way..... i'm digging it however yeah wanting to absorb as much info as i can.

and yes this is my current jeep. i got it new-ish... and took 4 months to uncover a painted over ground wire that was wreaking havoc with my electric and shorting everything out. something so simple and took ages to find and correct.

 

[caryw5150]

When you say x average during city driving, are you driving primarily in a city? With 37s and a heavy wheel, I could easily imagine low teens if your truck primarily saw city miles.

Editing, just noticed your avatar. Yeah, massive MPG hit on that setup assuming that is your truck. Not only due to the poke drag and weight, but also the aggressive offset forcing your tires to fight themselves to track straight given our limited adjustability.

yeah thats my truck and yeah mostly city.... however 13mpg seems ridiculous. i'm waiting on the ECRI to try to calibrate the speedo.

 

[staying_tuned]

yeah thats my truck and yeah mostly city.... however 13mpg seems ridiculous. i'm waiting on the ECRI to try to calibrate the speedo.

Can you post details on the wheels & tires? If you're at 150lbs+ per corner in the city, it takes quite a bit of energy to get them rolling after each stop. Do you happen to have the last alignment result print-out?

On-road dynamics, general capability, fuel mileage, maintenance and more would be improved significantly if you were to pivot to a light 35" setup with more offset.

 

[Rusty PW]

you do this EVERY fill up?

I do on every fill up.

 

[Escape.idiocracy]

you do this EVERY fill up?

I do. We only have diesel vehicles, so I suppose it’s an easier habit for me.

But we add a fuel additive to every tank, log the quantity of gallons, fuel station, odometer and trip, price per gallon etc.

New diesels use high pressure fuel pumps- this, in conjunction with the new? 2005??ish fuel change to ultra low sulfur diesel (removed a lot of lubricating properties). In my opinion- a fuel additive should be added to each tank.

“If” a fuel pump fails, it sends small metal particles through the system. When this failure happens, the entire fuel system needs to be replaced. This literally costs around $6k.

I figure the added cost of $100 or so a year for a fuel additive isn’t too much for some added protection.

 

[Escape.idiocracy]

yeah thats my truck and yeah mostly city.... however 13mpg seems ridiculous. i'm waiting on the ECRI to try to calibrate the speedo.

So, you really aren’t getting 13mpg….
Your computer system is displaying 13 because the rotations per mile are off. The transmission also isn’t shifting at the correct points either which is making matters worse.

Speculation- but you are probably around 16-18mpg.

Just think how bad your fuel economy would be if you opted to buy a gas jeep….. the added cost of fuel and initial expense up front will still intersect/break even between 20-30k miles making your return on investment worth it.

 

[@californiajeeping]

So, you really aren’t getting 13mpg….
Your computer system is displaying 13 because the rotations per mile are off. The transmission also isn’t shifting at the correct points either which is making matters worse.

Speculation- but you are probably around 16-18mpg.

Just think how bad your fuel economy would be if you opted to buy a gas jeep….. the added cost of fuel and initial expense up front will still intersect/break even between 20-30k miles making your return on investment worth it.

This is correct. My speedo is exact dead on. I drove checked with gps and adjusted till it was correct dead nuts on. I hand calculate my fuel used per miles and its within .5mpg of the computer.

Im getting 20-22mpg Mixed mostly highway driving in the mountains with 38" patagonia's and icon beadlock wheels!

If I lived in florida where its flat and people drive 60mph I would easily get 24-25MPG.

These engines are amazing.

 

[maddocmuc]

That mileage is horrible. I am at 26 mpg with the diesel. It must either be this recall diesel filter thingy or you run over a tacoma and are dragging the wreck under your car around wirh you. Dare a look beneath….

 

[Thomaas]

I have a 2021 Dieseland my around town mileage is 22 mpg and my hwy is 25-30 mpg

Same here...got 34+ on the way back from Sonoma County to San Diego County.

 

[Koolcarguy]

2021 Jeep Gladiator diesel on 37's getting 13-14mpg in city driving. wondering if there are issues anyone knows could be causing. drives fine. no issues as i know it, aside from tiny gas tank, reported fuel mpg is horrible.

That's horrible i get 23 24 on the highway and have the same setup on my Rubicon 37's my Sport s gets 26 27 on 35's my wife get 30 on her 21 Rubi Jl but she drive like a little old lady lol

 

[Koolcarguy]

Stock axles / Evo Enforcer Overland w/ King 2.5's. I daily drive it with beach cruisin' being my primary offroad activity. I do have a trip planned to the Hot Springs off road park next month.

Sweet Gladiator!!!

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