Bought 96 grand cherokee laredo 4.0 4x4 for My Son as a first car,
jeep may have been a mistake! poor kids spending all his money on fuel just to go to work
replaced plugs, wires, cap and rotor still 8MPG what is the the deal with a 6cyl getting 8 MPG??
it passed the smog/DEQ Test

 

Is it all stock? May be time for o2 sensors. I get 10mpg on a good day but it was worse until I changed my driving habits

 

If it's lifted with big tires on it, that could be the reason.

 

30/9.50-15 Tires
3" spring block lift
120,000 miles

I'll check into the 02
Thanks

 

No, the tires aren't big enough to cause a decrease in fuel mileage. My 97 ZJ got about 10.5 when doing my newspapers, but that's stop and go about 250 times in 3 hours, so I didn't expect much more. On the highway I got around 14 to 16. That's with 3.73 gears and 225/75R15s. Those are about 28.25" tall.

 

Driving style can make a lot of difference to MPG - heavy right foot maybe ?
Also check for binding brakes.
Worst I've ever got from my 2000 WJ 4.0 is 11.8 MPG in the depths of winter on trips no more than 2 miles.
Regular MPG is about 13.8 on mostly short trips & town driving.

 

With my cherokee 4.0L I usually only get about 10 mpg in the city. 13-15mpg on the hwy. In the winter when i drive it, it usually drops considerably because I dont like cold cars and will start and idle my jeep for sometimes as much as 20 minutes. Also a young kid driving a car, i'm guessing he's hitting the pedal harder than he should be. Let him drive you car and you drive his for a few days and see if you can get better mpgs and see if your car has a decrease... But unfortunately these 6 cylinders are not known for efficiency. Also if he's driving around in full time 4wd that may affect it.