Dodge4me

I searched out the forum on fuel mileage posts and I am not getting near what most are saying they are getting.
This summer with less than 5,000 miles on the new jeep, we took a trip across the state, 600 miles round trip, fully loaded and got close to 17MPG.
I had to make an emergency run to Easter Montana (2,200 mile round trip, in two days I might add) by myself and barely got 15MPG. Doing the math, I was nearly 600 lbs lighter (no gear or other bodies). The only change to the jeep since this summer was the replacement of the front bumper and addition of a winch. I was at the speed limit except for climbing the passes, then just went as fast as I could without running the engine above 3,000 rpm in 4th gear.
Would the winter fuel mixture play this big a difference? Any other concerns I should be aware of?
I just can not believe a change from the stock, stubbified bumper, to a Smittybilt Mod center section only would affect anything like this.

Mark Doiron

Some random thoughts ...

* I see a drop of 2-3 MPG when I go the speed limit versus slowing down to 65.

* I see a gain of 1-2 MPG when driving at higher altitudes (as do my traveling companions in their 3.6 and 3.8 JKs).

* I see a gain of 1-2 MPG when I use mid-grade fuel over using regular grade that is lower than 87 octane (85-86 typically sold at higher altitudes, and ditto the companions remark above).

* Taking off on that last bullet, I've seen 86 octane fuel sold as regular at locations not all that high in altitude (especially in TX).

* Driving in windy conditions (25 MPH or so winds and higher) affects my gas mileage by as much as 2-3 MPG positive (tail wind) or negative (not a tail wind).

jk_sea

Point of clarification--4th gear for the steep grades, and 6th otherwise, right?

Winter fuel blend will drop fuel economy by 1-2mpg, all other factors pretty much the same.

Running I90 East/West can come with constant winds that run against or at the side of the Jeep. Especially running West, a constant headwind can murder fuel mileage. That's not uncommon this time of year.

Are you using the trip computer/ AVG MPG display? If that hasn't been reset in a while and you typically get bad mileage (around town, traffic), the trip mileage might not have been enough to pull that number up to accurately reflect your actual MPG during the trip. If you're calculating mileage by hand, a lot of people do it differently. Maybe explaining your method might help if you do it that way.

Our stock 2013 JKUR might get 18mpg doing that run. I just ran my 2-door w/ 33's and 3.73's, 6-speed, from Seattle to Idaho on I90, over T-Day weekend, and could barely eek 19mpg. Winds were very strong on the way home and I was seeing 17.9, 18.5, which is really low for my 2-door. It always bests the JKUR by about 1mpg, so yours doesn't sound too far off.

Tire pressure is also a big factor. Do you know what PSI you were running?

Anyway, your mileage doesn't sound too far off. Not for running I90 East/West with Snoqualmie Pass, Elk Heights, Vantage, pulling out of Spokane, or running any of the passes in Idaho (4th of July, for example). Along with wind, and cold temps.

rob_engineer

Did you remove the air dam? Mpg will drop noticeably if you did. Winter gas and col temps makes the MPG's decrease. Here is my mpg over 50,000 miles. 2012 JKU. Manual trans. 3.73 rear. Pretty much all stock.

Dodge4me

I was fortunate with the winds. Calm the whole way with a little headwind on the return east of Livingston for about 10 miles was it.
Good point on the computer display. I had not reset that in quite some time, and this is where I got this info.
The front air dam is off, but the Mod bumper has one built in, although I will admit this is a different shape and has holes in it.
I have the automatic, so was always in the highest gearing I could be.
I'll remember to reset my computer next time and see what happens.
Thanks for the advice!

jk_sea

I was also trying to remember...the speed limit on I90 changes to 75 at some point in Idaho/Montana. Like Mark said, 65 seems to be a sweet spot (depending on gearing, of course). The 3.6 really starts to dump fuel if you push it.

Dodge4me

I had a time critical issue so fuel mileage was not a concern but rather noticed. It was the run only to Spokane where I first observed the lower mileage but I had not reset the computer either.