Ok, new guy here. I recently purchased my 98 xj. Lifted 4.5-5 on 33's all stock motor, tranny, and gears.

I filled it up the other day for $60. So far I have driven 80-90 miles and half used 1/2 tank of gas. Didn't buy it for economy but this is extreme.

Any suggestions for improvement?

 

Re-gear it. Also, the bigger tires will make the mileage off if the speedo gear wasn't changed. I average about 13mpg stock. You could see about 8-10 with 33s on.

 

Don't forget, gas prices are going up and gas is getting crappier as we speak. Mileage for many cars is starting to tank. A full tune up would also help though.

 

My clock shows about 200 miles a tank on all stock no lift with 32's so I would say that's probably what you're gonna get.. .

 

At least attempt to do a search. There is a very recent thread with exactly the same vehicle specs asking the exact same question. Search for the same title you used.

 

01' Stock gears engine etc on 31's and I get 15-16 around town. My gauge is around half when I hit about 100 miles on a fill up. I get 250 miles to a tank if I hold out till the last second and put 17.5 gallons in.

Fill up with half a tank or more and you pick up a MPG give or take.

 

I also have a set of 31's that I think I'm gonna put on today to see if I notice a difference. All in all the jeep runs good. Rides like a brick though. Haha. Might try new plugs and what not today. Got to wait for the temp to get up.

 

New plugs & plug wires may help a lot. My buddies TJ was only getting 10mpg until we installed new plugs & plug wires. Got anything on top of the XJ? Moving my 33" spare tire off the top increased gas mileage by around 3 mpg.

Remember just changing tire sizes will make it look like your gas mileage improves because the tire diameter changes. Larger diameter tires turn slower at the same speed than a smaller diameter tire. It'll look like your getting a couple miles more to the gallon when in fact you're getting almost exactly the same mileage. But big tires do weigh more and create more wind resistance.

My '98 XJ is on 33s but the differential gears were changed to 4.56. The speedometer now reads correctly and the odometer now matches mile markers on long interstate highway trips. I check mpg every tank and consistently get 14-16 mpg.
hth, Doug

 

WOW! $60 to fill up???
I just filled mine up and it cost me $80 here in south TX. I can get anywhere from 275-300 miles on a tank of gas.

 

I am averaging 14 - 19 mpg 99 totally Stock.

 

I'm averaging 10-12 MPG with 32s an a lift it sucks

 

I'm about 11-12 mpg and I have 4.5 lift and 33s. Highway I get about 14-16

 

Seriously it's killing my wallet

 

Re gear it. Spend money to save money! Or get smaller tires. Plus there are a lot of little things you can do to increase it

 

I'm not sure if it was regeared by the po and I've done everything but a new 02 sensor