Before I did the lift and other goodies, I would see 25-29mpg highway -- not joking. That was stock height (about a year ago), my '96 with a 4.0l, 90k miles, 235/75R15 Michelin LTX MS2s, AX-15 5spd, 3.55:1 gears (3.07s did much worse). Now, with 4" of lift 235/75R15 Hercules Terra-Tracs, same trans and gearing, a 9500lb winch and winch bumper, and a Hi-Lift jack mounted on the back of the luggage rack, I am lucky to crack 21mpg; most of the time it is 18mpg highway and about 16mpg in the city, which is telling me the bumper has the coefficient of drag all screwed up! I am going to build a removable airdam and see if that brings some of the MPGs back. Oh, I forgot to mention, I am also running the 703 injectors and a full-length header, which both together helps quite a bit, too.

2000 4.0L Automatic

Just under 170k miles

Avg 19.28 mpg

All stock. Tires 235/75/15

Shell V-Power

Schaeffer 10W-30 Synthetic Blend

All Schaeffer fluids.

Techron ran threw it every oil change.

Champion plugs

I can get 400 miles to a tank on a good week.

Last month average 31.1mpg 2.5 diesel,if fuel wasnt like £1.38 litre/$2.14 id go for 4.0 but never happen unfortunately.

87 2 door 2.5, 5 speed 4x4
237,000 miles
Average 19 mpg between driving around town and wheeling
Bone stock except for some 235/75r15 Treadwright Crawlers

35 1250 15s, 456s, rear locker, heavy bunpers, 19.6mpg avg

88' 4.0, 3.5" on 31's
227xxx on odometer
16-17 highway and backroads
CAI
87
Quaker State 10w 30 non synthetic with Lucas oil additive
Wish I could get better mileage but don't have time to get new injectors

01 / 4.0l / auto /110k mi bone stock engine airbox & paper filter ? ngk v power plugs / 33's /stock gears
best of 17mpg

running it at 2200 to 2300 rpm on the open road.. it sucks gas like their is no tomorrow in town stop and go

99 with 93 thousand on it, k&n filter, catless, and flowmaster, stock height, 235/75/15's and im think I'm getting about 12 to 15 around town, mostly with windows down, and atc turned off...horrible I know

The amount of time it took you to write this post....you could have bought or even installed your new injectors....just being a smartie

Is it just me or is anyone else blown away at the variation for the close setups as I am....some stock ones are 12mpg....one guy said 26 (4.0)....the average seems 16 or so....hell stock my 01 saw 20mpg mixed...lifted and 31s at 35psi I get 17.5 doing speed limit .....19mpg doing 65.....3.55 gears

1990 XJ
No mods/stock tire size
220k miles
15-16mpg mixed if I don't run the A/C and 13-14 if I do.
Don't have any highway milage numbers yet.

Oh wait.........I did upgrade the injectors but, it doesn't seem to have noticably affected my mpg. All it did was increase throttle response, it idles better now and cut the crank time before it starts way down.
Before..........the time between me turning the key to engage the starter and the engine to start running was about 4 to 5 seconds.
Now...........less than 1 second.

2001 Sport, auto
140,000, 235 tires, no lift
17 ish banging around, best is 20.46 mpg on the road

Throttle body spacer, cowl cold air - no difference in mileage

Synthetic tranny fluid - worse mileage (that experiment lasted about a week)

New upstream O2 sensors, electric fan, took off cross bars, changed all the fluids - lifted the average from 15 mpg when I first got it.

Regular gas,cleaned the fuel system with 3M kit, Rotella Dino Oil, Champion Platinum plugs

year of jeep -1998 Sport I-6
miles on the odometer - 106K
your mpg - when completely stock 21 mpg hwy 17-18 mpg city since mods 18 -10 mpg hwy & 15 mpg city
mods you have done - 3" lift, replaced front bumper with off-road bumper, replaced rear bumper with off-road, receiver hitch and tire swing bumper, rock rails.