Lately I have only been getting about 21.5 mpg in my 98 auto. Anybody have any ideas on how to improve this?

 

What mileage were you getting before? Assume this is highway driving or ....?

AFAIK very few get that or more than that, so maybe YOU should give us ideas on how to improve.

 

buy a 4 cylinder car.THat mileage is very good for a jeep

 

Sorry I was joking. Just wondered if anyone else is getting 20s. I am really happy with it and it is better than my moms 2006 grand v6. My jeep is mostly stock for now and my mpg im getting is why.

 

I have a Scan Gauge and it seems to be pretty accurate. When I drive on the highway between 60-65 mph I get 24 to 24.5 mpg. When I drive 70-75 I get 20-21 mpg. This is on relatively flat 100 mile stretches of highway.

When I first got the XJ, 3 months and 3000 miles ago and pre-scan gauge, I was getting 12.5 mpg around town and about 19 mpg on the highway. After a tune-up and adjusting my driving habits by using input from the scan gauge my around town mpg is between 15-16 once the engine is warmed up to operating temp. For quick trips where the motor doesn't warm up I get about 10 mpg.

I've had one off road excursion of 32 miles where I averaged 8 mph and 8 mpg.

 

Drive downhill more often.

 

Anything about 20mpg is about the best youll ever get in it.

 

If your XJ is bone stock it may go high teens or even 20. If lifted/larger tires/roof racks/etc. it goes down sometimes way down.

I also have a Scan Gauge and my XJ has a lot of extra added wind load/rolling resistance/weight not conducive to "Good" fuel mileage in any way. But I never had ant intention of building this for mileage just off road use.

That said all of my mileage figures increased considerably when I changed gears to 4.56's. When I'm unloaded nothing inside I can get 17.6 on highway/city which I feel is very good. In town it drops to 13 at best with AC on. When loaded with all gear for the trail 13.9 mpg hiway, 10 mpg on trail 2wd, 8.5 mpg 4wd in hilly (some quite steep climbs here in the Ozark Mountains) and rough terrain.

Don't know what others are getting but I'm pleased with mine overall, just wish my range was more in 4wd before I have to go back to the trailer and refuel. I can carry up to 3 55 gal drums of fuel on the front of my trailer but then have to use the 1 ton diesel F-350 to pull it.