Really good gas mileage

I usually average around 30 to 33mpg with a mix of highway and city.




But that is with a 2.5 and a 5-speed.;) Now if I gave it a tune up and didn't drive as hard I could probably get close to 40mpg.

My wife drives a 98 4.0 auto stock and gets 20-22mpg.

The off roader with 4.10's and 36" tires gets 12-14mpg.
 
I was working a job exactly 90 miles from my garage to the parking lot. I got two round trips, 360 miles, on 15.5 gallons of regular, over a time period of two months, so it was repeatable for accuracy. My '92 is happy on regular. The '96, however, likes 89 octane, and I haven't verified it, but seems to get better mileage on better gas. I know an unsophisticated engine like the 4.0, at least the HO version, doesn't have knock sensors to retard timing, so maybe I'm dreaming. Of course, PA uses 10% ethanol, which lowers MPG, but maybe the better stuff has less?
 
85xjwoody said:
I usually average around 30 to 33mpg with a mix of highway and city.




But that is with a 2.5 and a 5-speed.;) Now if I gave it a tune up and didn't drive as hard I could probably get close to 40mpg.

My wife drives a 98 4.0 auto stock and gets 20-22mpg.

The off roader with 4.10's and 36" tires gets 12-14mpg.
Click to expand...

I don't believe you
 
I use to grip about the mileage my XJ's got but I just bought a new 09 Hemi Commander and it only gets 12 in town, 20 on the highway and thats driving it like a old man! We have a 08 JK and its dismal as well and also anemic compaired to the Hemi and 4.0, but it still runs very good though. I get 16 in town and 21 on the highway in the JK.

My 1990 RENIX is the best mileage maker at my house. I get 16-17 in town and 22-23 on the highway. It is a "all new" 1990 though, there is nothing that has not been replaced or modded in the last 2 years.
 
I have the window sticker for my '96 Country hanging on the wall, and it says 15 City, 19 Highway. They only recently offered the 'combined' number, which I think is the figure the C4C deal went by. Although, the more you read into it, the more it was abused.
 
93_xj said:
My jeep: 97, 4.0 / AX-15 / 200,300 miles.

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/advice, or anyone else who gets really good miles out of their jeep?
Click to expand...

It sounds like you're doing really well with your MPG's, but I don't think you're calculating correctly. You say you put in 18 gals from empty. Unless you coasted, or were towed, in with no gas, you were not empty. My '96 has a 21 gallon tank. So you may have had a 3-3.5 gallon cushion.

The most accurate way to calc your mpg (assuming you gps'd distance as well as speed to verify odometer accuracy) is to pick your favorite spot, at your favorite station, and use that same spot, pointed in the same direction, as much as possible. Fill up, and let it stop at the first auto-shut off, or second, it you like, but be consistant, don't take it up to the next even dollar amount. Let it shut off by itself. Reset your trip meter to zero.

Drive yourself down close to empty, then fill up in the exact same way again. Now divide the trip miles by how much gas you actually burned; that will give you your mpg. You have to measure what you used, not what you started with, because you weren't empty when you started, and you weren't empty when you finished (close to empty, on an analog gauge, is not a precise way to measure consumption).

Pre gps days, I would verify odometer accuracy by running 100 miles according to highway mile markers vs. what the odo logged, and calculate a correction factor. I've also found that the speedo error, and the odo error are not always off by the same percentage (i.e the speed is off by 5 %, and the odo may be off by 3%).

Don't get me wrong, I'm not trying to bust your stones. The reality is most people aren't all that interested in this level of accuracy, but if you want bragging rights, make sure you can back it up with analytical, not anecdotal, data.


Steve
 
winkosmosis said:
I don't believe you
Click to expand...

It IS a 2.5. 2 less cylinders that need fuel my friend. Do the math, thats 1/3 less gas that needs to be used (give or take). Not sure if you can really compare it like that, but it does make it more believeable. If he was getting that with the 4.0 HO...I wouldn't believe him...but his readings for those are accurate :sunshine:
 
It would be important to know what size tires 93_XJ is running, and is he sure that his odometer is correct.

If he's basing his numbers on the way he described his fillups, they're suspect due to his flawed methodology. There are a lot of variables to consider, and I'm wondering how he obtained his figures.

p.s. Where has 93_XJ been? It's been two weeks.
 
Last edited:
85xjwoody said:
I usually average around 30 to 33mpg with a mix of highway and city.




But that is with a 2.5 and a 5-speed.;) Now if I gave it a tune up and didn't drive as hard I could probably get close to 40mpg.

My wife drives a 98 4.0 auto stock and gets 20-22mpg.

The off roader with 4.10's and 36" tires gets 12-14mpg.
Click to expand...

BTW, how are you cranking out your numbers? Define "close to 40." I'd like to believe it, but I gotta :phone::bs:
 
SteveT said:
BTW, how are you cranking out your numbers? Define "close to 40." I'd like to believe it, but I gotta :phone::bs:
Click to expand...

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?

As far as close to 40, I have not gotten over 33mpg. I could POSSIBLY get close to 40mpg if I gave my jeep some new plugs, wires, cap, and rotor as they have not been replaced in awhile. That along with my driving style, if I were to drive without so much gas pedal and stayed away from the highway I could get better than 33mpg hoping for 40mpg.

I fellow jeeper I know drives an xj very simular to mine and gets around 36-38mpg but rarely hits the highway as our jeeps on the highway are at 3000rpm at 70mph. Not good for mpg.
 
85xjwoody said:
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?

As far as close to 40, I have not gotten over 33mpg. I could POSSIBLY get close to 40mpg if I gave my jeep some new plugs, wires, cap, and rotor as they have not been replaced in awhile. That along with my driving style, if I were to drive without so much gas pedal and stayed away from the highway I could get better than 33mpg hoping for 40mpg.

I fellow jeeper I know drives an xj very simular to mine and gets around 36-38mpg but rarely hits the highway as our jeeps on the highway are at 3000rpm at 70mph. Not good for mpg.
Click to expand...

That's better than most compact cars.
 
Yes it is. I don't have much power in the 2.5 vs the 4.0 but taking my time on the back roads to work instead of the highway helps my mpg bigtime. It is only an extra 15 minutes to work without taking the highway.
 
85xjwoody said:
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?
Click to expand...

No, that sounds right, similar to my method, assuming you try to be as consistant as possible. Much better explained than 93_XJ. If you're sure your odometer is reading true (verified by mile markers or GPS over a long distance, 50+ miles), then you've earned the best mileage claim. I emphasize the odo check, because 215's are tiny. I've heard that some rigs came with them stock, but you could could be reading over if your tire's true diameter isn't equivillant to stock.

Jeep On
 
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.

I use the same method to calculate, fill tank - drive till gas light comes on - fill tank and divide the miles on the trip OD by the gals of fuel I just put in.

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.
 
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