Only getting 12-13mpg on stock JK - JeepForum.com
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post #1 of 47 Old 02-15-2016, 09:52 AM Thread Starter
MikieB
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Is this normal for a 2012, 2-door, auto trams, completely stock, no lift or big tires? I am very frustrated with the mpg's. I knew it wouldn't be the greatest going into it, but didn't think it would be that bad. I get roughly 190 miles between fill ups. Granted it's been extremely cold here the past 3-4 days with single digit temps. Mostly all my driving is city stop and go traffic. Even in the summer, I never saw greater than 14mpg. I am out of warranty or I would take it to the dealer. Very disappointing. I am considering trading for a Subaru Crosstrek at this point.


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post #2 of 47 Old 02-15-2016, 10:45 AM
propped1
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Subaru?

In a 12 you should be in the high teens probably for your type of driving. the 3.6 is more efficient than the 3.8. Also 4dr and 2drs have different tank sizes. 4dr has a bigger tank (22.5 gal), so to claim 190ish you are actually getting far worse than 14mpg if a 4dr. The fuel gauges are designed to look emptier than they are, though. Cold weather will also drop performance.

I have an 07 and average 13mpg with plenty of highway mixed in to compensate. Mines not stock though (lifted, heavy tires, steel armor all the way around, winch). 07s have the 18.5 gallon tank in 2dr. Most of the time I cant put more than 15ish gallons in mine when I'm below the E. I have a 215~ mile range, pure highway, depending on wind direction (14mpg). My dash says I get 12.7. You need to actually do the calculation to really know. Also stay off the skinny pedal.

Gas is like 1.45/gallon though, so really... WGAS?

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post #3 of 47 Old 02-15-2016, 10:54 AM
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Quote:
Originally Posted by SteelBlueTJ View Post
Is this normal for a 2012, 2-door, auto trams, completely stock, no lift or big tires? I am very frustrated with the mpg's. I knew it wouldn't be the greatest going into it, but didn't think it would be that bad. I get roughly 190 miles between fill ups. Granted it's been extremely cold here the past 3-4 days with single digit temps. Mostly all my driving is city stop and go traffic. Even in the summer, I never saw greater than 14mpg. I am out of warranty or I would take it to the dealer. Very disappointing. I am considering trading for a Subaru Crosstrek at this point.
Stop-n-go will drag the mileage way down, especially if each trip is somewhat short.

To see if it's a problem with how the Jeep is running, plan a highway trip long enough to use most of the gas in the tank.

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post #4 of 47 Old 02-15-2016, 11:19 AM
rha600
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I can tell you that small things make a HUGE difference in the MPG on the Jeep. Kind of like what ron said about about the stop and go.

Another example, if I stay at 60-65 on the highway I get around 18mpg. great for a Jeep with a 2.5 lift, 35's and a new front bumper with no air deflector...but if I go to just 70mph my economy drops all the way to 13.8 and at 75 it's in the high 12s.
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post #5 of 47 Old 02-15-2016, 11:21 AM
JIMBOX
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yup, Make a trip as rj suggests, but

Pick a town, more than 50 miles away/w a certified mile distance from city limits to city limits--start with full tank and drive to (XX) city limits--turn around and drive back to your home town, same station/same gas--fillup and divide mileage by gal of gas= mileage-

I've done that a dozen times /w tire/wheel/lift/gear changes--don't use your speedo/computer for miles, or MPG-always off by at least 5%

I get 14mpg around town and 17 on freeway--that's with an auto and 5.38 gears

Good luck

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post #6 of 47 Old 02-15-2016, 11:44 AM
nighowl2000
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winter gas and stop and go traffic is really hard on gas mileage with the j/k. Also stay from ethanol based gas. The 3.6 runs like crap with that gas. get some injector cleaner too

mine: 2014 jku sport S

her's: 2010 commander sport 3.7L 4x4
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post #7 of 47 Old 02-15-2016, 11:53 AM
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Quote:
Originally Posted by nighowl2000 View Post
Also stay [away] from ethanol based gas.
Most places don't offer that option.

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post #8 of 47 Old 02-15-2016, 11:58 AM
222Doc
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seems way low, his summer mpg is more telling. i mean my 2012 pile gets 14-17 in town on 35"s with 4.5+ lift front, auto with 4.1, topless door less, if it matters highway depends on speed. can be as low as 16ish at speeds 0f 75+ and like 20 at 55. cant drive 55, never could.

the only thing i can think of off hand if its not driver<< could be leaking valves it is a 2012, mine died at 20K. they extended the warranty i think to all these years12-13? or was it just the ones that failed? cant recall. but if you have this issue it can have a performance hit. should toss codes though. anyone of the miss fire codes to the multi miss or even ratio mix out of range, seemed to happen at 7k+ feet and up with the valve issue then.

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post #9 of 47 Old 02-15-2016, 12:26 PM
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I have a 2 door auto 2012 with 34s and 3.73s my thingie stays around 14.6-15.1 with all stop and go driving highway driving goes up from there I would get gas a diff station and maybe even try diff octanes.
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post #10 of 47 Old 02-15-2016, 01:42 PM Thread Starter
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Thanks. Yea I always try to use better gas. I usually fill up at Sunoco with regular 87. I put Lucas fuel injector cleaner in on every other tank even though I see no difference. I know the winter gas blend doesn't help, but there's no getting around that. I don't tow anything and don't have a heavy foot either. Today it read 12.8 MPG on a 40 mile round trip. I always suspected I have the bad cylinder head known on the 2012's, but my Jeep never threw the trouble code yet. The dealer said they won't do anything or even check it out unless it throws the code. I heard bad MPG's are symptom of that issue, so I guess it is possible.
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post #11 of 47 Old 02-15-2016, 02:38 PM
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like JIMBOX said - don't use the dash MPG figures. I took my 08 auto Rubicon on a 200 mile highway trip. at 65 MPH, the jeep got 18.8. the return trip was at 75 MPH and the mileage dropped to 14.8. the dash readout was under 12 MPG for both legs.

again, like JIMBOX says "divide mileage by gal of gas= mileage".

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post #12 of 47 Old 02-15-2016, 03:36 PM
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You need a different dealer. My dealer did the recall while they had it for the multiple windshield issues. No codes and no indication of anything wrong. They just told me about the recall and did it while they were changing out the windshield frame.
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post #13 of 47 Old 02-15-2016, 03:50 PM Thread Starter
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Originally Posted by cranbiz View Post
You need a different dealer. My dealer did the recall while they had it for the multiple windshield issues. No codes and no indication of anything wrong. They just told me about the recall and did it while they were changing out the windshield frame.
I'm not 100% sure, but I don't think they ever issued an official recall for the cylinder head. I always thought it was a fix it only when they throw the code kind of thing.

I do use the calculation to figure out my true MPG at every fill up, but it's funny I always find it to be pretty close or the same as what the display reads, so I've always taken it to be pretty accurate, at least for me.

On a side note, I test drove a used fully loaded 2014 JKU Sahara w/ 12k miles this afternoon just to compare. It's very nice and definitely tempting me. It read 16.8MPG on the speedometer. I told the sales guy I would think about it being $13k difference with my trade. I felt like I could almost get into a brand new one for that.
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post #14 of 47 Old 02-15-2016, 03:56 PM
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Maybe it wasn't but I do know that my dealer did it and the jeep wasn't throwing codes. Could have been due to the fact it was in warranty and they were trying to keep me happy.
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post #15 of 47 Old 02-15-2016, 04:46 PM
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Quote:
Originally Posted by SteelBlueTJ View Post
I'm not 100% sure, but I don't think they ever issued an official recall for the cylinder head. I always thought it was a fix it only when they throw the code kind of thing.

I do use the calculation to figure out my true MPG at every fill up, but it's funny I always find it to be pretty close or the same as what the display reads, so I've always taken it to be pretty accurate, at least for me.
You are correct. It's only a TSB, extending the head's warranty, and guiding the technician through the troubleshooting for certain codes related to the left head.

My computer mpg readout is accurate, too, if I subtract 1 mpg from the display. It has been consistently 1 mpg optimistic compared to hand calculations. I quit keeping track of every tankful's mileage, which I did as a barometer of engine performance. Now I keep an eye on the displayed average, looking for a drastic change, hand calculating a tankful only once in a while.

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