XK Fuel Economy

[jantrit]

OK guys I get it, big V8 low MPG. That said what are you guys getting gas milleage wise? If you have mods that will effect it for instance if you are on a 2" lift with 33's let us know.

By the dash computers and mixed highway / city:
06 4.7 QT-II - 13.3 MPG
06 5.7 QD-II - 11.3 MPG

[Sal-XK]

OK guys I get it, big V8 low MPG. That said what are you guys getting gas milleage wise? If you have mods that will effect it for instance if you are on a 2" lift with 33's let us know.

By the dash computers and mixed highway / city:
06 4.7 QT-II - 13.3 MPG
06 5.7 QD-II - 11.3 MPG

That seems to be about right. With my mods that's about what I get with the 4.7. Sometimes I get better but I drive pretty slow and don't get stuck in traffic and have about one light between me and my work.

[WanderingTs]

I have found my mileage to be VERY dependant on tire inflation. I have found for longer highway driving, if I overinflate to 45-50psi (well within tolerances of the tire, just more than Jeep recommends) I get 15-17mpg depending on terrain (not by the dash computer, but by gps miles traveled/gallons used). At 40psi, that goes down to about 13-14 and at 35psi about 12mpg. 40 and 35psi are estimates, it has been a while since I actually ran that psi on the road to check. I find it is worth the trade off for the little rougher ride to save the $$, especially since some of my favorite wheeling areas are a couple hours freeway driving away from home.

So far I am having no uneven tire wear (a sign of true overinflation) and be sure if you are going to try higher psi u stay within what the tire is designed for.

[Matt]

I'm in the 12-13 range, mostly city with some highway on my 07 5.7L, added mods/weight and agressive tires.

But im not heavy on the throttle, though i don't granny it either.

Depending on the mileage, you may be due for plugs and other maintenance that'll revive some of the lost mileage. If that 5.7L is stock, i bet it needs some plugs, pcv valve and some fluids changed.

[pjmjr508]

2" BB lift with skids & also using the Flashpaq on Performance and mostly city driving and get about
12 mpg

[LWM]

I am consistently in the 10 to 12 range and you can see all my mods in my signature. With the big tires and all the steel on my Jeep I think I do pretty good.

You can add fuelly to your signature if you keep track of your actual fuel-ups and it gives you the accurate reading (mine is 10.9 mpg).

[NeilSmith]

gas mileage......LOL !!!!!!!!

[jantrit]

I am consistently in the 10 to 12 range and you can see all my mods in my signature. With the big tires and all the steel on my Jeep I think I do pretty good.

You can add fuelly to your signature if you keep track of your actual fuel-ups and it gives you the accurate reading (mine is 10.9 mpg).

fuelly....nice hadn't seen that before.

[peteyturbo]

The wife usually drives the commander, and every time I get in this thing it is between 9.8 and 10.8 max which is comical really. I have tried everything to get better economy as far as maintenence (New oem plugs, afe intake, cat back exhaust,pcv, all fluids, seafoam, ect.).. Driving in the city 90% certainly does not help, but the best possible economy I can get at highway speed is about 16 with MDS fully kicked going slightly downhill while hitting the reset button..I keep telling myself it is the tire size skewing the numbers but lets be honest, it's not gonna be anywhere near as much as I would like..

[Matt]

The wife usually drives the commander, and every time I get in this thing it is between 9.8 and 10.8 max which is comical really.

lol well there's your problem!!

I'll get between 14-16 depending on my speed on the highway... if i keep it around 70-75 its closer to 14mpg for me. Drop down to 65-70 and it'll climb to the high 15s.

[NeilSmith]

I keep telling myself it is the tire size skewing the numbers .
What size tires are you running ? I went up to a 245/75 and the odometer readout is about 20 miles different from the gps with a full tank( if I remember right ) . That is definitely enough to skew your mileage if you're using the dash display. If I want to check the mileage, which I never really do, I use my GPS.

[Matt]

^^ I was going to say the same thing because if you're running a 31" tall tire, that would make his MPG of 16 go up to 17.1.

But i checked one of this threads and i believe his tires are only 1/2" taller than stock.. a 245/65/17 if i remember correctly.

[wookie]

The Wife averages 14Mpg with mixed highway/ city. She drives like she stole it. If the ECO comes on she just goes faster. I have milked 21.8Mpg on the highway doing 60ish, bone stock and no roof rails.

[Sal-XK]

She drives like she stole it.

LMAO that's hilarious!

[wookie]

She drives like she stole it

I picked the Commander out for me as a tour gift..........She rarely drove the 06. So she did "steal" it from me.....:(

[Adondo]

When I first bought it, mine was at or around the 20's on the highway. I once posted a photo of the computer showing 20.8 MPG after a day trip.

Now? With a lift kit, 265/70 M/T's and roof rack catching the air? It's doing fantastic to get 14.5 on the highway, and 10 in town. BTW, the tire guys said those M/T's would "negativity impact the MPG." They weren't kidding.

On edit: I've reset the speedo with the Hyperchips programmer, so it matches the GPS. That means it REALLY DOES get as crappy of MPG as the computer shows. :mad:

[Matt]

On edit: I've reset the speedo with the Hyperchips programmer, so it matches the GPS. That means it REALLY DOES get as crappy of MPG as the computer shows. :mad:

Yeah I've noticed that I always have to put in a smaller tire size to get the speedometer accurate since the tire flexes with the vehicle weight.... so for my 245/75/17 that are supposed to be 31.5" tall I had to put in 30.5 to get my computer to read accurately. That works out being right too if you follow most programmers instructions; they say to measure from the center of the hub to the ground to get the true "effective" radius of the tire and double that for the programmed diameter.

A lot of people just put in the tire diameter based on size... always makes me wonder if their reported mpgs are a bit inflated because of that... (though its only about .5 difference in most cases. Still food for thought)

[Lt_JWS]

Well guess i shouldn't complain.... I get around 15mpg driving the on the roads around here, on the highway I get 18(without roof racks), I just ordered a AEM intake for $172US shipped(new/amazon!) that should get me another MPG and my ported Throttle body should breath easier!

[Adondo]

A roof rack and its catching the air profile does make a difference.

As for the tire diameter, I just went for a road trip, and "messed" with the tire size a bit at a time until it matched the GPS in speed and distance. The programmed value is written down somewhere, and isn't a match to the actual tire size. It's black magic to get perfect I guess.

[TrialByFire]

I'm getting 14-17 MPG highway--corresponding to 80 mph and 60 mph respectively.
In town, it's more like 10-12. My Fuelly average (including off-roading) has dropped to about 13.5 with all the mods.