City I usually get about 15-16. Mixed 18ish, hwy typically low 20s
Currently, 1989 Renix XJ 4WD, stock engine/trans/t-case, Ford 5.0 injectors, strokedjeep.com 60mm TB, magnaflow 14" 4x9 oval muffler with turndown, 4" lift 31" bridgestone AT 693s, 4.10 gears.
I got basically the same mileage stock with 235/75s.

 

Last time I checked 70 divided by 10 was seven!

 

gas mileage can also be severely affected by tire type such as all terrains and mud terrains.
for anyone now looking at this and wants to know how to do their mileage, if they have stock gears, it is...
(Current tire size) DIVIDED by (factory tire size)....MULTIPLIED BY THE MILES ON THE TRIP.... DIVIDED BY THE AMOUNT OF GALLONS.

IE- (31/27) x 266 = 305.40.... then inserted 14 gallons... comes out to about 21.8 MPG.

keep in mind this is an example and if you can get 21 mpgs with 31's....

 

My Brown 1984(1st year) Cherokee with 252,215 miles on her worn out and original GM 2.8V6/Chrysler 3 speed auto, 3.73 gears 3" lift and 31" WilddCountry TXR tires gets around 9-10mpg around town, and maby 15 out on the Highway if driving on the flats or downhill. My Black 87 Cherokee(one of my commonly driven Jeeps) has 294,425 miles on her original everything including 1st year 4.0, 1st year AW-4, 1st year NP242, Dana 30 front 3.54 gears, Dana 44 rear with 3.54 gear turning worn out WildCat 215/75 R15 tires gets maby the Best fuel mileage out of my 6 Cherokees, with 17-18mpg around town, 19-25mpg on the Highway. My White 96(other commonly driven Jeep) has 249,528 miles on her 4.0, AX15 5 speed(recently torn apart by myself, only to replace 3rd gear syncro, and reverse idler bearing) (New clutch plate, disk, pilot&throwout bearing, etc also) 3.07 gears with Toyo 235/75R15 gets Good MPGs also with proabably 15-18 around town and 19-22 Highway(Of course All depanding on the way She is Driven). My Red 2 wheel drive 99 has a freshly Built 4.0 (After 139,??? miles on this motor, before needed repair)Broken in Very Well over her last 820 miles, AW4 4 speed auto with 3.55 gears in her Rear is 15-18 average around town and as Good as 22.8 on the Highway with GoodYear 235/75R15 tires . My Beloved 2001 SilverStone Metallics 64,829 mile 4.0, AW-4, NP231 and 3.55 geared Low pinion Dana 30 front- Chrysler 8 1/4 rear turning YokoHama M/T 30x9.5R15 tires, and gets not so Good fuel mileage as the others with 12-13mpg around town 19-21 Highway, but has the most Power of these 4- 4.0 InLinerz. My Red 1984 Cherokees 2.5 hasnt Run in 5 years, so I cant report Her MPG.

 

3 inches of lift and 31's, around town I get 10, on a good day I get 15 highway. Don't really give a crap, if I did I'd be a Honda/Toyota owner, I'd rather deal with gas mileage I hate, to drive a rig I love rather than be one of those ******** who hate their car but are the first ones to brag "my car gets 35 mpg", yeah thats cool, but your car sucks! Your car sucks, you suck, and you should try having some fun sometime, its pretty cool.

 

Unless something screwed up I just got my first measurement of "almost pure" highway driving, with only a little bit of city travel... 28.6 MPG!!! 1999 stocker 4.0L and AX-15

 

How in the hell is that possible? Lucky!

 

I've done 350 miles on a full tank of straight highway no traffic driving. Generally an xj isnt horrible on gas. Depends what you running and how you're driving her. I'm averaged 230 a tank since I have 235/70/16 still. I know that'll go down in the future

 

I drive very hilly rural and mountain roads. My mileage sucks. For some reason, this week I averaged like 10 mpg if not less. I don't know what happened there. I usually get about 12 or 13. Would a rise in temperature do that? It went from being about 60s to 70s.

 

That's only 11 mpg

 

Wierd