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questions about MPG and tuning

3K views 23 replies 12 participants last post by  Pumpkin Wrangler 
#1 ·
So, I just took a trip from Jacksonville to my home in Panama City. At highway speeds 65mph with minimal traffic from the time I topped off till my fuel light came on was 210 miles.... or 13.4mpg by my calculations. I have 33"MT tires and a banks ram air with flowmasters catback. I have seen people running 37s on 4 drs and get better mileage then that.
Now, I understand its a jeep and about as aerodynamic as a brick. But 13.4mpg is a bit extreme. Any suggestions for issues or is this completely normal?

Fixes I should look into?

Any info would help. Thanks in advance!
 
#5 ·
I drive a 2014 Rubicon with a Banks exhaust, Banks intake and a Bullydog tuner and with stock tires I was getting 19 mpg combined driving. I just went to Nitto 295-70-17s and went down to around 17.5-18 range. Did you change your tire size to match your tires?
 
#6 ·
So i did a quick search. From gas station to gas station is 225 miles. I bought 15.6 gallons of fuel. So thats 14.4mpg not 13.4. But still very shitty... no my Speedo isn't calibrated to the larger tires yet. So my odo said I traveled 210 miles when I actually traveled 225. Any suggestions?
 
#8 ·
Lol your getting like 110 mile more out of your tank then I am... and im on 33s with a 2 dr...
 
#9 ·
A couple of ideas. Lots of people running "E" rated tires run them under inflated to improve the ride. That will be more comfortable, but hurt fuel mileage.

A true mud tire will cost you about 2 mpg over an AT tire of the same size.

I still think you drove a bit farther than you think. If your speedo/odometer is calibrated for factory 29" tires the circumference of the 33's are about 12% larger. So 210 miles X 1.12= 235 miles driven. That would put you at 15 mpg. Remember, your speedo is off by about 12% too. That means you were averaging closer to 73 mph than 65. My Wrangler does pretty well as long as I'm under 65. Over 65 and it sucks gas even with 32" AT tires.

If your Jeep is calibrated for factory 32" tires then your speedo/odometer is only off by around 3% and your fuel mileage really does suck.
 
#10 ·
Haha! Yeah I had the factory 32" tires. Although im not 100% thats what my jeep came with... I run my E rated tires at 34psi. Higher then most... but not the 40 recommended
 
#12 ·
Those are honest quotations there lol. It was always bad. My dash would say 16.5 on highway
 
#13 ·
Request a build sheet from Chrysler to find out exactly what came from the factory. If it came with 16" wheels and 29" tires and everything is calibrated for that size then you are better off than you think. If you were to recalibrate for what you have I don't think you'd be that bad. If you were to actually drive 65 mph I'd expect 17ish mpg with that set up, 19-20 mpg with AT's. Driving closer to 75 with mud tires and around 15 mpg is to be expected.

If it came with 17" wheels and 32" tires it is close enough to not worry about recalibrating and you know you need to look elsewhere.
 
#22 ·
Request a build sheet from Chrysler to find out exactly what came from the factory. If it came with 16" wheels and 29" tires and everything is calibrated for that size then you are better off than you think. If you were to recalibrate for what you have I don't think you'd be that bad. If you were to actually drive 65 mph I'd expect 17ish mpg with that set up, 19-20 mpg with AT's. Driving closer to 75 with mud tires and around 15 mpg is to be expected.

If it came with 17" wheels and 32" tires it is close enough to not worry about recalibrating and you know you need to look elsewhere.
You guys were right. 16" wheels. Wow im not too bad off then haha.

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#14 ·
How would I request a build sheet?
 
#15 ·
Got my 15 JKUR a liltle over a month ago and so far have about 1300 miles on it. Still basically stock, majority of the miles being done in the city with stop and go traffic to and from work(for now, been too busy to go off-road). I'm getting 15.6/7 MPG according to the info center. Highest I've seen it is 15.9, yesterday, after taking a small highway trip. One of my coworkers got a stock 2007 JKU X and is getting 17+ and is much heavier on the pedal than I am. I know things like the 44 front/rear axles, 3:73 gearing will prob decrease it some but at times there's a 2mpg difference. Normal?

Re: after looking around some more I guess this is completely normal. Stupid question. Guess I just need a bigger gas tank AND to stop looking at my so called MPG's.
 
#17 ·
Got my 15 JKUR a liltle over a month ago and so far have about 1300 miles on it. Still basically stock, majority of the miles being done in the city with stop and go traffic to and from work(for now, been too busy to go off-road). I'm getting 15.6/7 MPG according to the info center. Highest I've seen it is 15.9, yesterday, after taking a small highway trip. One of my coworkers got a stock 2007 JKU X and is getting 17+ and is much heavier on the pedal than I am. I know things like the 44 front/rear axles, 3:73 gearing will prob decrease it some but at times there's a 2mpg difference. Normal? Re: after looking around some more I guess this is completely normal. Stupid question. Guess I just need a bigger gas tank AND to stop looking at my so called MPG's.
I'm seeing between 15.5 and 16.5 mpg on stock Rubicon tires with 4.10 and 6 spd in 50/50 mixed city/highway driving. Have 2,000 on it now.
 
#18 ·
Soft top and always travel with it on
 
#19 ·
I called Chrysler and they are going to email my build sheet to me.

I also found out the original owner was enterprise.... fantastic lol....
 
#20 ·
I think I rented your Jeep! You do not want to know what I did to it. :)
 
#24 ·
You can't call and get the info I tried that.
Go to the jeep website, contact us, and you want to do the email request form. You need the last 8 of your VIN and some other info. I requested mine Saturday night and got it this morning.
 
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