2019 JLUR 3.6 8speed, 4.88 gearing with 37/12.50/17 Getting 11.5 MPG

[CarbonSteel]

Wait.....really? I have only ever heard cruise was a gas saver. How isn't it?

Because when you approach any incline it will downshift as many gears as necessary to hold the set speed. When that happens, the RPMs go way up and MPG goes way down for as long as you are on the incline.

As the driver, I can allow the Jeep to slow down (some) and not do all of the downshifting. The cruise control will always err on the side of maintaining speed versus considering the MPG.

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[guarnibl]

I’m getting around 11 in town with my 392 on 37” heavy ass Nittos. Crazy the OP is getting the same with a V6.

13.8 according to my EVIC.
4.56 gears.
37" KM3s w/ Tazer.
Mostly city but not much stop/go.
Highway (65-70) was returning around 16.

I guess one thing to consider is I'm just starting to pass break in -- it will go down.

 

[DogsRule]

 

[beaups]

What am I missing. I see so many of you posting with the same setups and averaging 14 to 16 MPG.

I have changed the tire size and gearing using the Tazer. Speedo is correct and I am averaging 11.5 mpg in town. And on a long road trip I might get up to 13 mpg.
Is there any additional changes that I am unaware of?

Thank you,

Have you compared the digital speedometer speed with a GPS? There have been other reports of people thinking they calibrated and it not taking affect (didn't follow restart procedures etc). That would cause your speed/distance/mpg to be significantly under-reported.

 

[Paul Judge]

I have the factory 4.10s with heavy 37"×12.50 nitto rg's at 32 psi in a all stock 3.6l with @7000 miles on it average 15.2mpg American running at 60-63 mph perfect conditions with small hills or rises. Drops significantly with cold Temps or wind...

 

[DUNE RAP]

Is that hand calculated based on actual gallons pumped and miles driven or is that number from the computer?

Either way, it does seem a little low but everyone’s situation is going to be different and you may just have a heavier foot than others. Hell, my Jeep’s computer is reporting about 11 mpg average right now and it’s bone stock.

OMG! My 2021 JLR gets 21-22 mpg!

 

[Steph1]

Not sure it was mentionned, but the lower the tire pressure, the most resistance you create. I run my 315 at 34psi on 17x8.5 inch rims.

 

[oldcjguy]

How many miles on the motor? My mileage went up significantly after several thousand miles. When I first got it I was averaging 13-14 around town (2.0T rubi stock 4.1 and KO2). Now I average 17-18. I've noticed that with my last few cars. They seem to perform noticeably better after 7 or 8 thousand miles.
A few suggestions to try if you have not....
Have your oil analyzed, see if anything strange comes back from that report. That could tell you if there is something wrong with the motor.
Pull the diff cover and see if there is a strange or bad wear pattern on the gears. (bad install?)
Are your brakes possibly dragging? (does the jeep pull left or right)
Is your ebrake dragging after the lift?
How's your alignment and tire wear?

 

[aldo98229]

Well, yeah, the cow had millions of years to perfect its aerodynamics...!

Both are equally susceptible to cross winds, however.

 

[roaniecowpony]

Well, yeah, the cow had millions of years to perfect its aerodynamics...!

Both are equally susceptible to cross winds, however.

Even the crudely human created barn has better aerodynamics than a Jeep. So, when someone says "a Jeep has the aerodynamics of a barn, I say: "Not quite".

 

[Outsider87]

I was getting about 12 mpg average with Yukon 4.88, 37" Cooper STT pros, method 701 wheels, and a Mopar 2.5 lift. thought that was a drag. Then threw on the gobi rack to get 11 mpg. im watching this thread pretty closely for any improvement at all. I do know i have my Tazer set to 37. something. maybe dropping it down to a more accurate radius. we shall see.

 

[lepcat]

Forget all the of f topic comments.
OP, you set Tazer wrong your MT Mtz37s have a rev per mile of ~565 .
Calculation of the diameter to use in Tazer should result 35.6 diameter. Iterate on that number slightly using your GPS or an app for your phone to make sure the MPH is close to the speedo reading in your Jeep. AND - make sure you input to Tazer the correct gear ratio for the diffs.
Pretty simple: Find the RPM and the diameter formula by using Google
By the way with a huge search for as many companies I could find selling 37" tires the average RPM came out 565+/- a couple.

Thank you for the suggestions. The gear ratio is set correctly. I’ll play with the sizes a bit for tires. I have a little road trip today and putting pen to paper again on mph.

 

[CarbonSteel]

Even the crudely human created barn has better aerodynamics than a Jeep. So, when someone says "a Jeep has the aerodynamics of a barn barn door, I say: "Not Quite right".

Fixed it for ya

 

[beaups]

Thank you for the suggestions. The gear ratio is set correctly. I’ll play with the sizes a bit for tires. I have a little road trip today and putting pen to paper again on mph.

Easiest check is to download a gps/speed app for your phone and compare to the digital speedo in the cluster. I'm guessing they aren't even close.

 

[lepcat]

Easiest check is to download a gps/speed app for your phone and compare to the digital speedo in the cluster. I'm guessing they aren't even close.

speedo is/has been spot on as mentioned in the original post. I have a couple of GPS speedo apps for that very reason. It’s the reason I’ve still been looking for some kind of issue causing the lower than average mph compared to very similar builds.

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