that's how i drive? haah, i don't know. my old man gets around 9 as well with the same setup as me, 2010, 2 door auto 4" w/ 35's.

 

I have 37s with 5.38s and get 13.5. No superchips yet.

 

i'm getting about 12mpg around town with my 35's

 

I have been keeping track of highway fuel mileage at different stages of my JK build up, and here is what I have found:

all stock, suspension, 255.75R-17 tires with 4.10 gears: 18 mpg
2.5" suspension, 35x12.50R-17 Goodyear MTR tires with 4.10 gears: 12 mpg
2.5" suspension, 35x12.50R-17 Goodyear MTR tires with 5.38 gears: 15.5 mpg
2.5" suspension, 35x12.50R-17 Dick Cepek Fun Country tires with 5.38 gears: 16.5 to 16.9 mpg

So, it apears you get much better gas mileage if you gear your Jeep lower to compensate for the bigger tires, because you will be able to keep your auto trans in high gear more of the time on the highway.

You will also get much better gas mileage by choosing an AT tire instead of a MT tire.

 

I have also been keeping track of my mileage as I have gone through different stages in my build. I have a 2008 Rubicon 6 speed.

All stock I was getting 15.5 mpg

With a K&N drop in filter I got 16.6 mpg

With a 3.25 lift and 37x13.50 Toyo MTs I got 14.98 when I corrected my mileage to account for the larger tires

After adding the Superchips Flashpaq I saw the following

15.36* with the 87 tune
15.07 with the mileage tune

I just switched to the 91 tune and am running 93 octane gas. I got 15.94 mpg at my last fill up. Right now it looks like I will be getting between 16.5 and 17 on the current tank of gas.

With the manual and 4.10 gearing, I will say that my gas mileage on the highway at 70-75 is as good as if not better now than it was stock. Stock in 6th I would be running 2700-2800 rpms and was getting horrible highway mileage. Somewhere around 15.6. I got the same highway gas mileage with my 37s before the Superchips flash as I did stock.

I have found that the sweet spot for mileage on these Jeeps seem to be around the 1700-2000 rpm range.

ETA * The gas mileage with the 87 tune is a little bit high. I was still dialing in the tire size in the flashpaq. I probably was much closer to 15 mpg.

 

hes what i got
2010 JK 4 door X
3.21 gears
stock X rubber
Bestop trektop
2.5 BB liift
Daystar hood "wranglers"
6 speed manual

my computers average is .. drumroll.... 21mpg!

it went up 1.5 when i added the trektop

i know guys that say teh automatic will eat gas mileage like its nothing... the 6 speed seems to help big time on gas milage - that and a light foot.

 

Who wants to have a light foot?

 

wanna cry? calculate your mpg yourself over your next couple of tanks. I don't believe there's a single JK dash readout that it's generous by a couple of mpg. i would bet you're getting 19 mpg.

 

Sahara unlimited with auto 3.73 gears 3.5 lift, K&N air intake gibson exhaust and hypertech programer on 87 octain and speedo recalibrated.

hand calculated driving easy combined city and freeway 17.5 it is best at 70 in OD any slower and it will lug, anything under 65 and I need to turn off the OD or It will backshift on inclines or head winds, driving with out thinking of fuil economy and I loose about 2mpg
The dash is within .5 mile per gallon accurate, I can get 19 to 21 on a freeway trip if there is no wind or inclines, If I pull a utility trailer with 4 dirt bikes I would be lucky to get 14mpg

 

2009 X 4-door Auto, 3.73 ratio
4" lift
35" Toyos
K&N drop in filter
Superchips tuner 87 tune

= 14.23 to 15.5 mpg mixed city/hwy

Stock I was getting 19/20 mpg (hand calculated)