MPG in a heavily built JK, 40s/D60s, not your typical MPG thread

[highoctane]

Planning my build that I'll be having done on my JK. One thing I'm considering is some kind of extra gas tank, like the ARB long ranger. (Que the overland jokes) The Evo lever is in my build, so it obviously can't be a tank that mounts in the rear. Currently, on 37" MT/R Kevlars on Raceline beadlocks, and a 3" Teraflex longarm system, I get about 14-17mpg hwy at 70mph, and near 300 miles per tank. My question is for you guys like Eddie and Greg on heavily built JKs on 40" tires, corner armor, heavy tire carrier, coilovers, D60 axles, etc. What kind of MPG, or better yet, how many miles per tank are you guys getting on the highway? Is it so bad that you wish you had an extra fuel tank, like the one ARB makes, when you go on long drives(like the JKX, heading to MOAB, etc)? Has running low on fuel on the trail on longer runs ever been a legitimate concern for you? The cost of fuel isn't really my concern, as much as the useablility of a JK with a sub 200 mile per tank range is.

 

[Prime8]

An important detail might be which engine you've got. EVO Jeep and Moby both have the 3.8l motor, whereas the new 3.6l gets better mileage and has more power.

 

[highoctane]

An important detail might be which engine you've got. EVO Jeep and Moby both have the 3.8l motor, whereas the new 3.6l gets better mileage and has more power.

I have a 2008 with the 3.8, 6 speed trans.

The build list so far is Dynatrac PR60 axles/ARB lockers/5.38 gears and high pinion/FF rear, 20" Raceline Monster beadlocks, 40/15.50/20 Nitto Mud Grapplers, Evo DTD front coilover system, Evo lever rear with DTD, Evo full corner armor and tire carrier, Rock Hard sport cage, Atlas II xfer case, 1350 drive shafts, Evo rock sliders, Evo 1/4 pounder front bumper w/stinger, Warn Power Plant winch, Mastercraft Baja RS front and rear seats. Considering an LoD narrow width rear bumper to run with the Evo carrier. It will be a heavy JK with the parts I'll be using. If I had to guess, 6500-7000lbs. Still planning it right now with the shop that will be doing the build.

 

[wayoflife]

it really depends on how i drive and the kind of terrain i'm on. anyone who knows me knows that i prefer to push the speed limit and when i do, i maybe get about 8-9 mpg or, about 180 miles before the light to get more gas comes on. now, driving more conservatively say, 65-70 mph on the highway, i've been able to get more around 12.5 to as much as 14 mpg - about 200-230 miles before the light comes on. having said all that, i typically go off the 200 miles per tank and plan all my trips accordingly. as you know, we do a lot of remote exploring and in places where gas is in short supply but, with planning, it has never been a problem for us.

 

[SAR JK]

"JK with a sub 200 mile per tank range"

10 MPG would suck! I'm also very interested in this answer. I'd like to ask what octane do you run?

 

[wayoflife]

An important detail might be which engine you've got. EVO Jeep and Moby both have the 3.8l motor, whereas the new 3.6l gets better mileage and has more power.

this is true, the 3.6 pentastar does much better in the mpg department.

10 MPG would suck! I'm also very interested in this answer. I'd like to ask what octane do you run?

we run 87

 

[highoctane]

it really depends on how i drive and the kind of terrain i'm on. anyone who knows me knows that i prefer to push the speed limit and when i do, i maybe get about 8-9 mpg or, about 180 miles before the light to get more gas comes on. now, driving more conservatively say, 65-70 mph on the highway, i've been able to get more around 12.5 to as much as 14 mpg - about 200-230 miles before the light comes on. having said all that, i typically go off the 200 miles per tank and plan all my trips accordingly. as you know, we do a lot of remote exploring and in places where gas is in short supply but, with planning, it has never been a problem for us.

Thanks for the reply. Just the kind of info I was looking for. 12-14 doesn't sound too bad, and is actually what I got on 37" tires before I regeared my JK to 5.13 gears. I rarely drive 80-85 mph, usually only on the downhill drive from Prescott to Phoenix, 5000 ft drop in elevation in 70 miles, so it doesn't kill mpg that bad, and the speed limit is 75, so I practically get run over on I-17 doing 65-70. 180-240 miles per tank, depending on speed, is pretty good. I was actually expecting you to say more like 140-150, which would make me want the extra fuel capacity of the ARB tank.


Crazy thing is, my '95 Range Rover on a 3" OME lift, and 32" tires, got 12mpg, why, lol.

 

[wayoflife]

Thanks for the reply. Just the kind of info I was looking for. 12-14 doesn't sound too bad, and is actually what I got on 37" tires before I regeared my JK to 5.13 gears. I rarely drive 80-85 mph, usually only on the downhill drive from Prescott to Phoenix, 5000 ft drop in elevation in 70 miles, so it doesn't kill mpg that bad, and the speed limit is 75, so I practically get run over on I-17 doing 65-70. 180-240 miles per tank, depending on speed, is pretty good. I was actually expecting you to say more like 140-150, which would make me want the extra fuel capacity of the ARB tank.


Crazy thing is, my '95 Range Rover on a 3" OME lift, and 32" tires, got 12mpg, why, lol.

LOL!!

just for kicks and giggles, we drove our big white jk up to the oregon border on 395 once trying to maintain a constant 55mph. if i recall, we got upwards of 15.5 mpg. that's probably about the best we ever saw in our current state - shy of drafting a semi, down hill and with the wind behind us. :crazyeyes:

seriously, we've gotten it figured out enough that we don't even carry jerry cans with us like we used to.

 

[piginajeep]

Cindy must have been driving. No way in hell YOU got 15 mpg

 

[wayoflife]

Cindy must have been driving. No way in hell YOU got 15 mpg

:cheesy: No lie, on our way out to Drummond Island, the roads were all flat and we were forced to pretty much do the speed limit all the way there. We got 15 mpg then too. :yup:

 

[highoctane]

LOL!!

just for kicks and giggles, we drove our big white jk up to the oregon border on 395 once trying to maintain a constant 55mph. if i recall, we got upwards of 15.5 mpg. that's probably about the best we ever saw in our current state - shy of drafting a semi, down hill and with the wind behind us. :crazyeyes:

seriously, we've gotten it figured out enough that we don't even carry jerry cans with us like we used to.

Nice. Sounds like the extra fuel tank isn't really needed at all then. I can live with those numbers, if mine gets anywhere near that once it's done.

 

[JKAnimal]

This is great info! I bought a 2012 JK Rubi U last December and I just ran my first set of trails Sept. 22nd-30th. After putting armor, bumper etc. my mpg dropped to about 17-18 on the highway and 13-14 in town. Of course I have a bit of lead in my foot. It has dual lockers, D44 front and rear and 4:1 ratio. I bought the manual 6 spd 3.6l penstar. I was really surprised to hear highoctane gets about the same mileage and range that I do.

 

[GCM 2]

I'm right there with Eddie. Typically around town I tend to have a somewhat heavy foot leaving the lights, it keeps me around 10-12mpg. On the hwy, it is very, very dependent on grade and head winds which can have me seeing numbers as low as 9-10mpg. Overall, I would say hwy driving for me is at 70-75mph, I get about 12-14mpg. And this I find very odd, much like a diesel truck, I don't seem to notice any increase or decrease in mileage if the jeep is carrying me, or four people, or all my off road gear for a long trip like a JKX. I do feel the extra weight/or no weight in seat of the pants performance.
.

 

[highoctane]

I'm right there with Eddie. Typically around town I tend to have a somewhat heavy foot leaving the lights, it keeps me around 10-12mpg. On the hwy, it is very, very dependent on grade and head winds which can have me seeing numbers as low as 9-10mpg. Overall, I would say hwy driving for me is at 70-75mph, I get about 12-14mpg. And this I find very odd, much like a diesel truck, I don't seem to notice any increase or decrease in mileage if the jeep is carrying me, or four people, or all my off road gear for a long trip like a JKX. I do feel the extra weight/or no weight in seat of the pants performance.
.

That's pretty good. I honestly expected you guys to get 10mpg it less all the time.