Ok so its a simple deed i know, but was just wondering...so about a 16.2 ish gallons to fill from when the light comes on and then reset your tripometer after a fill up...then boom the gas light comes on! Anyone know at what fuel load the light comes on? Or does everyone just see what mileage your sitting at once youve hit a 1/2 tank and just wing it? into if you know what I mean lol

Yeah mine does something similar.. Your tank is actually 20 gals.. I fill mine up and it never goes passed 3/4 full.. I just know roughly how many miles I can drive and I never go beyond 225 even though I could go more. I figure that way I always have plenty of gas. I also stopped calculating mpg's long ago it's to depressing.

fill your tank, keep track of milage, next time you fill your tank, divide milage by the amount of gallons taken to fill the tank.
there is no easier way.

your jeep odometer isn't 100% accurate even with stock size tires. so unless you use your GPS trip odometer, you won't be getting a correct value.

How much of a difference have you noted using the GPS? The official figures I've read are 14MPG city and 18mpg highway for the 4L I6 4x4, In the two weeks i've had mine i've measured 15.6mpg which was half highway (Vancouver to Whistler and back) and half city (uncongested) driving whilst entirely city (again uncongested) was 13mpg, not too far off the official figures.

i get around 12 city with a 4.5in lift and 33's om stock gears

i've seen them off by about 3-5 kph @ 100kph, so maybe only about 2-3 mph.
really, i guess it shouldn't make a huge difference.

I guess my daughter's 90 XJ is an oddball. Or maybe its the yellow paint. But she has been getting 23-25 MPG all summer. 4.0, AW4, 235/75R15s, and a functioning 231 and CAD. I believe the mileage is a little skewed as the original tires were 205/75R15s. I mention the yellow, as it stands out and likely keeps her speed down...

But her gas gauge is wonky too, even after swapping in the full gauge set. She doesn't fully trust it.

I usualy fill up when I need about 11-13 gallons.

Last time I filled up I got 18.74mpg . City and highway. Lucas fuel injector cleaner is where its at. Got my cavalier up to 31mpg from 27ish.

I'm usually a disbeliever in magic fuel additives... but in my "real life" I've had 2 people make similar statements recently... I've got a 440 mile trip to take today/tomorrow... I'll be grabbing some of this Lucas inj. cleaner before I fill up this afternoon.

Every fill up I do, I get around 16.4 and I run out about 300-365 miles with more highway and little of city. That's about 22mpg isn't it?

I have actually taken off my gas tank and made my own to where it can hold 30 gallons of gas.

ya i do the injector cleaner too but only an oil changes, think it helps a bit but has anyone heard of the cleaner stuff that you can put in your intake, oil or gas??? i swear i just read about it here somewhere...

Soldat,
I must admit I did not believe you... I mean, common' 2-3 mpg gain by adding some hocus-pocus... but, for $10 (for a 26oz bottle) I thought what could it hurt?

I typically get right handy to 17.75mpg on the highway, driving 70-75mph (2600-2800rpm)in mountainous terrain (steep grades) I drive this route once a week, 440 miles round trip.
I added the Lucas, filled the tank and headed out. I just filled the tank/got home. I buy gas at all the same stations, and always use the same pump (I’m weird like that) and always fill the tank till the gas is visible in the receiver… yes, wayyyy full.
Anyways, 20.95mpg!!!! Over 3mpg gain.
My rig has 170K miles on it, I run 33” super swampers, cut up fenders and aftermarket low profile bumpers (not very areo!)

Tomorrow I’m headed out on a 500 mile round trip with the WJ (4.7H.O.) which always gets right hady to mid/high 21mph driving 72mph… my trip tomorrow will be at 75-80mph… I will be adding the Lucas and will return here to report.
(WJ is bone stock with 72k miles on it)

I can understand using it to get the junk out but do you guys use that stuff every fill up to get that kinda MPG?