my 97 avg is 18 around town and i got as high as 26 here ,, stock, with 3 and 31's i get 16/22

 

My 99 4.0 auto 4x4 gets between 17 and 20, I just depends on your FOOT.

 

I get 15 MPG on my 89 Cherokee. Before I put big tires, gears, and stuff on it I got 18-20 MPG.
I think the following kills the MPG:
-TrueTrac Front & Rear
-31" tires
-4.10 gears
-HD bumpers (Weight)
-Rock sliders (Weight)
And of course vacuum leaks, exhaust manifold cracks/leaks...

 

Hopefully OP has made up his mind on that 89, considering it was 6 years ago.

 

Honestly, you'll probably get 10-14 mpg. City.

 

Just got my stock 01 limited and did 3 test. After picking her up and doing nothing to it, I let her starve by letting it run out of gas. I have a 5 gallon tank and filled it up and put it in and zeroed the counter, after that headed for 5 more gallons. I got 12 mpg till next shutdown. Changed the oil, both oil and air filters, plugs (FRZ5N), put a Lucas injector cleaner(on sale 2 for 5 in Autozone) and got all tires to 33 psi. Did 10 gallons again and got 15 mpg and one last time and got 14 mpg. It's a DD here in NYC, so half stop n go traffic and half highway.

 

Just did a 1074 mile trip in my stock 99. Had it pretty well loaded, ran at 73 mph, and got 21.78 mpg. The AC ran four almost 4 of the 16 hour trip.

 

Like said a long time ago if mpg's are a major concern don't buy a Jeep.

 

While mpg in the low 20s is nothing to brag about, I doubt any 4x4 vehicle equipped with a transfer case gets better fuel economy than a stock XJ.

 

Last time I calculated mileage I was at 11mpg. I don't DD mine but I just put a new pump in with a more accurate gauge. It seems to be getting better mileage than 11 though. We shall seeee