Really good gas mileage

[pikey77]

I get around 18-20 with my current 01.

On my old one the best I did was 27mpg on the way back to DFW from ABQ. Downhill with a tailwind. I usually stop to pee half tank........my bladder was about to burst!

 

[srimes]

fueleconomy.gov doesn't give the 2.5 a rating that's much different than the 4.0. +/- 1 mpg on the highway stick/auto. Not that those numbers vary...

If I'm in a hurry I get about 17 on my 30 mile highway commute, going 75-85 when possible. A more relaxed 70-75 gets me 18-19, and if I baby it I've seen 21. I have a 99 w/ 165k 4.0/auto, 2" lift 235s. That's with the crappy e10 they sell here. In Oklahoma I could get pure gas and did noticeably better than on the ethanol crap.

I'd love to get 25mpg. Maybe a new O2 sensor would help? It sure seems to run great right now, though.

 

[93_xj]

Hey guys, I just wanted to let you know that im about to make my 550 mile drive on Wednesday. Im gonna document it all with pics , ill report back. Its all gonna be verified by GPS also.

Gonna do a tune up before I go, make sure all my tire pressures are where they need to be, and put 18 gallons of gas in the tank and go.

Im heading from Hampton VA, taking I-64 West to Richmond , and then 95 all the way up to CT, and then I395 to my house in CT. Its 552 miles total.

Im gonna baby it harder than I ever have, extremely slow accelerations, cruise control at 65 mph ( i can usually go for 2+ hours at times without having to brake pending traffic) . I am also going to draft as many 18 wheelers as possible, and im running the tank bone dry. I will have a gas can with me to get me to a gas station when I run out. My best tank to date is 478 and I really think if i take it slow, and draft ( drafting is going to be really important here) that I will be able to make at least 490+ before I run out.

Should be fun

 

[JAS]

I could hit the low 20's while I was stock... Since the lift and tires... It is more like 14-16

 

[GarageAlchemist]

hey, XXXX you OP.

 

[93_xj]

why all the hate? dont worry, my MPG's will suck in 2 weeks. This is the last drive im making with it stock. Come friday its getting stripped and rebuilt. D44's locked f/r, 5.13's, 4.5" lift w/long arms and 35's on beadlocks. Gonna be lucky to get 15 high way.

 

[McQue]

running it bone dry can damage your fuel pump..
Why not fill the tank to the very top, record your starting mileage, run it to about 2 gallons left in tank, refill the tank to the very top, record gallons needed to fill tank to the very top, and divide gallons into driven miles right at that point?

 

[SteveT]

Hey guys, I just wanted to let you know that im about to make my 550 mile drive on Wednesday. Im gonna document it all with pics , ill report back. Its all gonna be verified by GPS also.

Gonna do a tune up before I go, make sure all my tire pressures are where they need to be, and put 18 gallons of gas in the tank and go.

...and im running the tank bone dry. I will have a gas can with me to get me to a gas station when I run out. My best tank to date is 478 and I really think if i take it slow, and draft ( drafting is going to be really important here) that I will be able to make at least 490+ before I run out.

Should be fun

My 93 xj 5-speed with a 2.5 is bone stock with 215 size tires and 4.10 gears. I calculate mpg by filling my tank, driving until I get close to empty, fill up, and do the math from my receipt. Take my miles traveled and divide by how many gallons I put in and there is my answer. Is there any other way to get MPG?

running it bone dry can damage your fuel pump..
Why not fill the tank to the very top, record your starting mileage, run it to about 2 gallons left in tank, refill the tank to the very top, record gallons needed to fill tank to the very top, and divide gallons into driven miles right at that point?

I still don't think you understand how to calculate mileage. The 18 gallons with which you start is irrelevant. Fill up. It could be one gallon, or twenty, it doesn't matter. Fill the tank until the pump stops. This is your starting point. You can then drive for an 1/8 of a tank, or a 1/2, or until you run out of gas if you're into fuel pump abuse. IF you choose to use a gas can, fill your spare can with a known quantity of fuel (i.e. start with it empty, and then note how much fuel you put in).

How ever far you go, when you get gas again, fill up the same way (auto shut off, plus one or two clicks, however you did it before). If you used the fuel can, add in that quantity of fuel to however many gallons it took you to top up. Divide the true number of miles traveled by the amount of fuel consumed. That's it. As long as your tank was full at the start, and full at the end, you can figure it out. This method works for one gallon of gas used (although that would be a little iffy, because any variables would be magnified), or over a year of fillups, as long as you're meticulous in your record keeping.

Let us know

 

[Joshooha]

alright this ain't rocket science here. If you can't calculate your fuel mileage, you probably don't need to be driving a motorized vehicle.

 

[93_xj]

Im not sure where you are thinking i am confused :shiver:

I put 18 gallons of gas in my jeep? Simple enough. The tank holds 18 gallons, it will not hold more than 18 gallons. Simple as that.

I drive X amout of miles, lets say 450 miles. Im running the tank dry. So I will have used an entire 18 gallons up. The tank will be bone dry.

I divide 450 by 18, and ill get 25mpg.

Its not hard, Miles driven divided by gallons used = MPG.


Im not trying to get an average over many tanks or whatever, I just wanna see how good i can do one ONE tank.

 

[heyhar]

My 2.5L 5spd gets around 20mpg. In my opinion the 2.5 has to work harder to move the box down the road and in the end uses just as much gas as a 4.0. My GF drives a 2.5L 5spd TJ and also gets about 20mpg.

My OHC normally shows about 22 -23 but I dont beleave it.

On interstate trips I find that I get the best milage around the 55 - 60 mph range and going past that drops the mpg's. At 70mph the engine turns about 3100rpms.

The physics behind this says it will take a certain amount of effort (gasoline induced heat) to produce the work- movement.

All our 4.0s turn 2000 RPM at 65 MPH. Your approx. 3000 RPM is proof that a similar amount of gasoline needs to burn to perform a similar task. There are smaller variables, like the friction of fewer engine bearings, and piston rings dragging on cylinder walls. This is where the smaller engine shines. But, when it needs to work harder, the advantage diminishes. Stretch it out over the life of the vehicle, and the larger, more under-utilized engine may last longer, offsetting the fuel mileage advantage of the smaller engine.

 

[themangeraaad]

Im not sure where you are thinking i am confused :shiver:

I put 18 gallons of gas in my jeep? Simple enough. The tank holds 18 gallons, it will not hold more than 18 gallons. Simple as that.

I drive X amout of miles, lets say 450 miles. Im running the tank dry. So I will have used an entire 18 gallons up. The tank will be bone dry.

I divide 450 by 18, and ill get 25mpg.

Its not hard, Miles driven divided by gallons used = MPG.


Im not trying to get an average over many tanks or whatever, I just wanna see how good i can do one ONE tank.

And you are 100% sure that it takes exactly 18 gallons? Not 17.75 or 18.5 or something else? If you fill up your tank to 18 gallons and drive for 3/4 of a tank of gas then fill up again you can do the same thing (except you don't end up filling up from a gas tank on the side of the road, not to mention running the tank dry can hurt your fuel pump. The fuel itself acts to cool the pump. No fuel = no cooling).

If you burn through 3/4 of a tank and then fill up again... the gas station pump will tell you how much gas it took until you were full again... so instead of dividing by 18, divide by however much gas you put in. So if you fill up and you put 14.87 gallons in... well take the # of miles and divide by 14.87.

Its safer (no potential damage to pump OR no danger to yourself which would be caused by you filling up on the side of the highway), it's more convenient (no filling up on the side of the road), and its more accurate (you don't know that your tank will hold EXACTLY 18 gallons, but you do know that the pump you just filled up using put exactly 14.87 gallons in (unless it is rigged to pump different than it reports, but that's a whole different story and not likely).

Anyway, you can do it however you like, I'm not going to argue... but I will say that I won't trust any numbers you report using your method (for all I know your tank holds 18.5 gallons which would make your numbers look better) and I also won't advise anyone to follow your method of measuring fuel economy

 

[heyhar]

Im not sure where you are thinking i am confused :shiver:

I put 18 gallons of gas in my jeep? Simple enough. The tank holds 18 gallons, it will not hold more than 18 gallons. Simple as that.

I drive X amout of miles, lets say 450 miles. Im running the tank dry. So I will have used an entire 18 gallons up. The tank will be bone dry.

I divide 450 by 18, and ill get 25mpg.

Its not hard, Miles driven divided by gallons used = MPG.


Im not trying to get an average over many tanks or whatever, I just wanna see how good i can do one ONE tank.

I may be wrong, but arent XJ tanks 20 gallons?
Anyway, replacing 18 gallons burned with 18 new gallons is the way to calculate it. I was working a job 90 miles away, two round trips, only four cold start cycles, almost all Interstate driving on a fillup, and averaged a repeatable 23 MPG. Without the little bit of in-town driving near my destination, I'll bet I could have seen 24. I think the key is filling the tank, and burning it off as quickly and efficiently as possible. Warm it up, jam the tank full, and you could conceiveably encounter no warm-up cycles, and minimal evaporation- no zig-zagging and sloshing!

I've driven our Subie Outback, rated 28 Highway, over 32MPG numerous times, by just driving sensible. But, putt around town, numerous cold start-ups, MPG tanks. It can be done, but under ideal conditions. Now that 'winter gas' is out, your MPGs may suffer!

 

[SteveT]

Im not sure where you are thinking i am confused :shiver:

I put 18 gallons of gas in my jeep? Simple enough. The tank holds 18 gallons, it will not hold more than 18 gallons. Simple as that.

I drive X amout of miles, lets say 450 miles. Im running the tank dry. So I will have used an entire 18 gallons up. The tank will be bone dry.

I divide 450 by 18, and ill get 25mpg.

Its not hard, Miles driven divided by gallons used = MPG.


Im not trying to get an average over many tanks or whatever, I just wanna see how good i can do one ONE tank.

The confusion comes from the fact that you are not empty when gassing up. I mentioned earlier that unless you coast into the station on empty, or get towed, you do not know how much gas is in the tank. For precise calcs, you can't trust the gauge. If you put in 18, but had two to start, you're now getting 22.5, not 25.
"Its not hard, Miles driven divided by gallons used = MPG." This is true, but gas put in does not = gas consumed.

 

[Bobby@Bullydog]

XJ Tanks are 20 gallons...so Steve T is correct on the mileage being 22.5 Which is still outstanding!

 

[SteveT]

XJ Tanks are 20 gallons...so Steve T is correct on the mileage being 22.5 Which is still outstanding!

Sure, excellent by most realistic standards, but nowhere near the 30+ claims in this thread. Again, I'm not out to whiz in any Wheaties, just be prepared to back up your claims with solid testing methods. Let's hear your (not you, personally, Bulldog) combination, and your processes for such stellar mileage.

Steve

 

[93_xj]

My best tank that I thought I had was 25 but I thought that was on 18 gallons. I see where im confused now, ill try the methods posted here and report back.

 

[heyhar]

My best tank that I thought I had was 25 but I thought that was on 18 gallons. I see where im confused now, ill try the methods posted here and report back.

It doesn't matter how many gallons the tank will hold, it's how many you've burned, in how many miles. Fill up, zero out the trip odo, drive, refill, do the math. The more miles on a tank, the smaller the rounding error. The more times repeated, better accuracy. Using the same pump at the same gas station-Priceless.
I haven't been able to see a hole in the original poster's method. It is scary to draft trucks- my life is worth more than a gallon of gas, though some may disagree. And as EVERYONE with an electric fuel pump should know, don't run your tank too close to empty.
Drive the Jeep at 55MPH, and I'd say your 25MPG claim is low. Mileage starts to drop exponentially above 50, especially our rolling bricks.

 

[CharlesS]

My jeep: 97, 4.0 / AX-15 / 200,300 miles.

People find it hard to believe, but im getting way better gas mileage than what Jeep advertised it at, and better than most other stock XJ owners get.

I live in Virginia but still go back to my "home" in Connecticut very often, so I make the 550 mile drive up 95 in my cherokee. I put 18 gallons in it, and routinely get 25mpg on these highway drives.

Is this unheard of or a common occurrence for a stock cherokee. A lot of people in my club find it very hard to believe that I can get 25+ MPG out of a cherokee.


I just made the drive today, put 18 gallons in from empty, and drove to VA. I got stuck in traffic on the Cross Bronx Expressway for about an hour, so I wasnt getting good mileage there, and then did a bit of city driving in NJ to visit my buddy. When my tank was at half, I was at 235 on the trip meter. I do 75mph or so and at 5th gear im running around 2100-2200 rpm's. When I stopped to get gas again, I was at 464 on the trip meter. Had I not been stuck in traffic, had I not did some city driving, and if I went 65 the whole way, and drafted some 18 wheelers, Im fairly confident I can get 500 miles out of 18 gallons of gas, which would equal about 27.7 MPG. Any tips of anything I can do to the jeep in terms of a tune up to squeeze a few more miles out of my tank? I really want to try and hit 500 miles. Next time I make the drive in November, Im gonna bring a gas can in the back and just run it dry so I can really push the limit.

Any tips/advice, or anyone else who gets really good miles out of their jeep?

When my 1998 XJ AX-15 w/ 108K was new.... the best MPG I recorded was 24 mpg on a trip to the Grand Canyon. Now if I can get 275 miles to a tank full I am surprised.

Have you changed to a tire size other than factory?

Jeeps dont have very good aerodynamics; about as good as a flying brick...
For you to get almost 28 mpg with a Jeep having over 200K on the engine is amazing to say the least....

If I was able to get 400 miles to a tank full I would be wondering if I did the math wrong...

Lots of things you can do to squeak out a little more gas mileage. Accelerate slow and smoothly, ensure tires are inflated to proper amount, ensure the engine is in good tune, change fluids in engine, transmission and differentials to synthetic, verify front end is aligned properly, drive with the A/C off and windows closed.

 

[kastein]

Im not sure where you are thinking i am confused :shiver:

I put 18 gallons of gas in my jeep? Simple enough. The tank holds 18 gallons, it will not hold more than 18 gallons. Simple as that.

I drive X amout of miles, lets say 450 miles. Im running the tank dry. So I will have used an entire 18 gallons up. The tank will be bone dry.

I divide 450 by 18, and ill get 25mpg.

Its not hard, Miles driven divided by gallons used = MPG.


Im not trying to get an average over many tanks or whatever, I just wanna see how good i can do one ONE tank.

This shouldn't be hard to understand... you have no idea how much the tank actually holds or has in it like heyhar said. The tank also is not dry when the pickup stops getting fuel - nowhere near. The closest I have EVER gotten was 0.6 of a gallon remaining (20 gallon tank, 19.4 gallons to top off) and that is because I ran out going straight downhill with the sloped bottom of the tank level. The only way you can tell how much you burned in the last X miles is to fill it up to the same point again and look at the fuel pump. You could technically do this with any distance and any amount put into the tank, but the measuring accuracy becomes less and less significant the further you go and the more you end up putting in the tank. So do like everyone has already said and run it till you have 1/4 left, then read the odometer and the fuel pump after filling up. Go to a dry tank if you like fuel pump abuse.

assuming your "18 gallon tank" is bone dry when you run out and then running your mouth about mileage numbers does exactly what assuming always does - makes an ass of you and me. Except I'm the one making an ass of myself right now by reposting exactly what's been said already in this thread about 20 times.