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MPG just sucks, am I the only one?

16K views 120 replies 82 participants last post by  jsherm007 
#1 ·
So I have a 09 2 door sport Manual. I have a 2.5 TF lift and 35ish inch duratracs. I have 4.88 gears and front and rear bumpers/tire carrier and rock rails. I currently get about 11-12 mpg going around town/campus which is lots of stopping and starting and rarely going above 40. On the highway I get maybe 13-14 am I am usually at cruise control at 75ish. Is it normal to get this horrible of gas mileage? I hear of people getting 16-17 easy around town but I have never even gotten close to that even when I was unmoved. Am i just an aggressive drive or is there something I just never figured out about getting better gas in a jeep?

I ask this because I am about to start having to commute 6 hours round trip per week and it stresses me out about gas cost and the potential of breaking down because my jeep likes to stick me with costly repair bills for no good reason and its about to get driven a lot more then usual.
 
#12 ·
sounds pretty normal to me.

I get about that in my truck, just be glad you arent paying for diesel.
Heck diesel isn't much higher then gasoline now a days. And it is actually cheaper for me to drive my diesel then it is my jeep and actually cost about the same per mile when towing my jeep.
 
#5 ·
I've got the teraflex and bfg 12.5x35's, 4.10's and an auto tranny getting 16 town 18.5 highway.

How much you tach @ 75mph?
 
#6 ·
You get bad mpg because A) you said a good bit of your driving is around town/campus hardly above 40 mph. This absolutely destroys gas mileage. Idling or continually stopping/starting and driving through city streets rips it apart in any vehicle. B) You go 75+ on the highway. The Jeep is a box. Most cars/vehicles see their ideal mpg figures (the EPA figures or more) at 50-55 MPH. The Jeep is even more so affected by this due to its horrible aerodynamics. Your lift is also hurting that.

My recommendation: slow down, and drive better. Not that you are a bad driver or not (who could tell), but if you really want to increase MPG, shift quicker, be easier on both pedals, coast more, don't idle, and mainly, SLOW down. You will see an increase of 2-3 mpg easy.

I had a Mustang GT before my Jeep, and routinely cruised at 75-80 and higher speeds on slower streets as well. The aerodynamics were better and while I traveled at higher speeds, I granny shifted usually to get there. I averaged 19-20 mpg on a V8. That was very surprising to most people. And yes, it was hand calculated and true.

In the Jeep, I've gotten 18.5 average on a fillup, but that was mostly highway. I routinely get around 17 each fill up, specs in sig. I do not let it idle, I do not shift above 3k rpms hardly ever. I take it easy. Highway 55-65 MPH.
 
#7 ·
You get bad mpg because A) you said a good bit of your driving is around town/campus hardly above 40 mph. This absolutely destroys gas mileage. Idling or continually stopping/starting and driving through city streets rips it apart in any vehicle. B) You go 75+ on the highway. The Jeep is a box. Most cars/vehicles see their ideal mpg figures (the EPA figures or more) at 50-55 MPH. The Jeep is even more so affected by this due to its horrible aerodynamics. Your lift is also hurting that. My recommendation, slow down, and drive better. Not that you are a bad driver or not (who could tell), but if you really want to increase MPG, shift quicker, be easier on both pedals, coast more, don't idle, and mainly, SLOW down. You will see an increase of 2-3 mpg easy.
This. Exactly.
 
#72 ·
"Any speed"? Not accurate. It's about the rpm's. If you're at 4k I the tach you are not getting high mpg.

My JK with 315s and 3.73 has a fuel efficient sweet spot around 67mph. Find yours. Keep your tach under 2200.

In my experience, if you want best Jeep gas mileage you need no lift, 33s max, taller gears 3.21 do well but 3.73 max.
 
#15 ·
Your new commute isn't just going to coast in gas but tire wear as well. IF you want to drive the Jeep I'd say go to 31-32-33" tires and re-gear the speedometer. More importantly ya got to slow down.....
 
#20 ·
Considering your vehicle, mods, and driving patterns your MPG is pretty good.
 
#38 ·
I've got a 2008 JKR with 2.5" lifts, 6-speed, stock 4.10s,several hundred pounds of skids plates underneath plus front bumper, 33" DuraTracs. My mileage is generally in the 13 to 15mpg range in town. To get closer to 15 requires keeping my foot out of the peddle and coasting on hills. On the highway I can get in the 17mpg range if I keep it under 70. At 65 I can get around 17.5-18 if I'm lucky (tail wind). Once I go above 70 my mileage goes down again.

I'm thinking some 3.8L just get better gas mileage than others. That is the only way I can explain folks with a lift and 35s getting 17 around town and higher on the highway.
 
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