3.6 Trash MPG

[Wbino]

I have a heavy foot with street capable wheels, because I'm on the street alot and I get an avg of 18 mpg. 75+ on the Parkway.

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[CooperBokeh]

Man. I know my gas mileage is aweful. I also have a 3.6 penstar engine and this is what I’m getting as of the moment of writing this…

 

[Deleted User 38384]

That's dashboard MPG - but I know it isn't much better than that. The trip north was 172mi and with 2 stops and no mashing of the go-pedal, I burned fairly close to 3/4 of a tank. The way home was just about 1/2 a tank. I've always driven fairly conservatively (coast to stops, don't tailgate/constantly brake) and even getting on the highway I'm not mashing it. I have a 700hp S6 for spirited driving. On the same exact trip, my 2015 1500 Silverado on 34s with a level, crew cab long bed I get 19.6 hand calc).

Different engine type, mine's an EcoDiesel, but I find the dash trip timer usually tells me about 1.2-2 MPGs better than I'm actually getting when I do the math at the pump.

A while back I did a MPG run, dash was telling me 40 MPGs, but the math at the pump came out to 33.45 MPGs. So if it says you're getting 13-15 MPGs, I'd have to imagine you're getting worse than that. Also too that's not even factoring in the 35s. You might be getting closer to 10-13 MPGs.

Like everyone else above me said, probably good place to start is getting your computer to recognize your bigger tires. And then honestly I would do some math at the pump.

Stop & Go traffic, and short distances isn't good for any vehicles MPGs. You might want to take it on a good long weekend highway drive, keep it down to 65, that seems to be the sweet spot for a lot of engines, and then do the math at the pump. Hopefully with all luck you'll be getting at least 17-19 MPGs, if not you can always come back here and we'll shoot some ideas around.

I'm assuming your vehicles' used? Have you looked up the Carfax on it or have you gotten it inspected by an independent mechanic. I wouldn't necessarily take it to the dealership and have them inspect it, dealerships are notorious for having stupid techs who don't know what the hell they're doing.

 

[Deleted User 38384]

Man. I know my gas mileage is aweful. I also have a 3.6 penstar engine and this is what I’m getting as of the moment of writing this…

I'm doing a slight bit of an MPG run right now.

Again different engine, I have the EcoDiesel, and I only just started my run yesterday.

I'm honestly expecting closer to 30 mpgs from the pump this run. It's winter in Texas, so I'm letting it idle a lot before I drive it. And that will kill your mileage!

 

[jack bauer]

22 Rubicon AEV 2.5 on 37s 3.6 motor.
Got back from a Death Valley trip (over 800 miles) recently was 18.6 average.

 

[Tncdrew]

'22 Willys. 3.6/auto, 4.56, 34" tires. Last July I did a trip from East TN to Loon Lake (CA) for an annual guys camping trip at the Rubicon.
Towed a small Uhaul cargo trailer full of camping gear. This is the trip info as I pulled back into my shop upon returning home.
Not too shabby I think!.
Oh yeah, that was during that intense heat wave the country was in at the time, (AC on continuously)

 

[Old Jeeper]

Hey guys - it's been a while but I am finally back in a JLUR and I'm having some issues with absolute trash fuel economy. My daily driving is 30mph or less for maybe a combined 3 miles so I'm not expecting anything great. Currently sitting around 13mpg (was around 10 with leaving it running during the winter). Did a roadtrip to my house up in Maine a few weeks ago, and the Lie-o-meter was 14.6 on the way (but there was a 30mph cross/headwind) and on the way home I squeaked out 15.6mpg. On the trip up, I went through 3/4 of a full tank of 87. Cruise control was set at 70 (which is actually 73) the whole time on the interstate, and up north was 10min trips at 35-55. Transmission had no problems hitting 8th and really never had to drop below 7th except for the occasional monster hill. The only thing to mention (mods below) is I have not adjusted my speedo for the tire height (but I've done the math).

2020 JLUR Hard Top
44k miles
3.6 Pentastar w/8spd
35" Duratracs @ 37PSI
PSC Bruiser Stubby with Warn Zeon 8-S
Factory rear steel bumper
No lift. No engine mods.

 

[Old Jeeper]

Hey guys - it's been a while but I am finally back in a JLUR and I'm having some issues with absolute trash fuel economy. My daily driving is 30mph or less for maybe a combined 3 miles so I'm not expecting anything great. Currently sitting around 13mpg (was around 10 with leaving it running during the winter). Did a roadtrip to my house up in Maine a few weeks ago, and the Lie-o-meter was 14.6 on the way (but there was a 30mph cross/headwind) and on the way home I squeaked out 15.6mpg. On the trip up, I went through 3/4 of a full tank of 87. Cruise control was set at 70 (which is actually 73) the whole time on the interstate, and up north was 10min trips at 35-55. Transmission had no problems hitting 8th and really never had to drop below 7th except for the occasional monster hill. The only thing to mention (mods below) is I have not adjusted my speedo for the tire height (but I've done the math).

2020 JLUR Hard Top
44k miles
3.6 Pentastar w/8spd
35" Duratracs @ 37PSI
PSC Bruiser Stubby with Warn Zeon 8-S
Factory rear steel bumper
No lift. No engine mods.

Overall you are hitting 15.6 at 70, not bad for a JLUR

My JLR hits 16.6 at 65 on cruise control with 4:88 gears and 8 sp & 35 Duratracs...I weigh LESS than you do!

 

[jax501]

'24 2-Door Rubicon; using Fuelly App and a very light foot.
~16 MPG HWY @ in factory stock configuration 3.6/33"/4.88/Auto
~<14 MPG HWY @ in modified configuration 3.6/37"/4.88/Auto/MC 3.5"/ECRI calibrated Speedo

 

[AZ Hella]

2021 JLUR 3.6L with the 6 speed here which, should be worse than your auto.
Actual 34" tires, stock 4.10's, 2" lift, steel bumper/winch and some skid plating and heavy sliders.
I get 16 mpg mostly city driving and will average 20ish on road trips.
Get it calibrated for the tires first.

 

[Nitehawk92]

I get pretty good mileage from my 2023 Rubicon 3.6 6-speed manual. I do drive conservatively, accelerate slowly, drive 65 - 70 MPH. I don't drive like a Prius driver though...

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