MPG thread

[jnaut]

12-14mpg in a very heavy traffic city
21-24mpg in highway/interstate

The better figures in highway are with warm and dry weather, A/C off, all windows up, 2 passengers and light luggage... no roof basket, no lightbar and 36psi in the stock SR-A tires.

Cheers

Conversely, I don't know how these guys do it who get well over the rated mileage. Good on you, brother, if you're getting 24. There's a bit of a myth with A/C, though. It's widely believed that it "kills" your mileage. It's been studied to death and overall, it's found to knock about 1mpg off your mileage rating. So don't suffer too much-- you're not saving that much.

But 24 and two passengers? I'm impressed.

 

[AlexKJ]

Conversely, I don't know how these guys do it who get well over the rated mileage. Good on you, brother, if you're getting 24. There's a bit of a myth with A/C, though. It's widely believed that it "kills" your mileage. It's been studied to death and overall, it's found to knock about 1mpg off your mileage rating. So don't suffer too much-- you're not saving that much.

But 24 and two passengers? I'm impressed.

Maybe is the way I measure it... In a empty section of the road, in a nice warm day with no wind, low alttitude, with cruise control in 62-63mph, I reset the EVIC and 12 miles later see it again... I know that the readings of the EVIC can be inaccurate, but what can I say... It's 100% highway at constant speed (with the high 42RLE overdrive), not an average...

Also my KJ is well maintained and we have a decent quality gas over here... and my wife has almost negative weight

Cheers!

 

[VTNomad]

MPG's

12 miles is hardly a large enough sample to calculate mpg's. It will give you a good, optimal mpg, but it won't give you a good average. The more miles you use to calcalate your mpg's the more accurate you mpg average will be.

I calculate my mpg's every tank. I reset the trip odometer and the EVIC, and I also do a rough calculation in my head to make sure the EVIC is accurate (it's never been off by 0.1 mpg). This gives me quite a bit of useful information; if my mpg's suddenly drop, I've either got a tank of low quality gas, or some maintainence needs to be performed. I had an Explorer before my Jeep and notied my mpg's went WAY down one day. Mice had gotten into the airbox and built a nest overnight. I cleaned it out, replaced the filter, and problem solved.

My best mpg average happened in August 2007. I drove from Limon, CO to Topeka, KS (460 miles). It was I-70, all interstate, all down hill, and with a very strong tail wind 30+ mph). The wind was probably the biggest factor. I've noticed a cross wind hurts my mpg's more than a head wind. I used the cruise control set 5 mph above the posted speed limit and the A/C was on the entire way, and I did not engage in any crazy drifting behind big rigs. I ended up with 24.2 mpg average.

On my way to work last summer, I drove from Purgatory Ski Resort (in Colorado) down into Durango, CO (close to 3000 feet of elevation drop in 30 miles) and average 38 mpg...on the way down. The drive back up every night kept my mpg average a little below normal.

 

[JeepJeepster]

Conversely, I don't know how these guys do it who get well over the rated mileage. Good on you, brother, if you're getting 24. There's a bit of a myth with A/C, though. It's widely believed that it "kills" your mileage. It's been studied to death and overall, it's found to knock about 1mpg off your mileage rating. So don't suffer too much-- you're not saving that much.

But 24 and two passengers? I'm impressed.

Its all about the terrain, the weather, and how you drive. Ive found my Jeep does the best this time of the year(in the spring and fall). Low humidity and lower temps really help it it seems.

If Im cruising down the hw at 55-65mph on flat, level ground, no wind, with the windows down, my scan guage will say Im getting 25mpg. As soon as I stop(stop and go traffic), go up a hill, pass someone, anything at all that includes giving it gas it will usually drop right down to 15mpg and even lower if it downshifts. Last night I was going up a fairly big hill in 3rd gear and it said 8.8mpg. It was having trouble holding 65mph and I was running 3500rpms(big hill).

I know the scan guage isnt 100% right but it gives me an idea of what Im getting. It was also dead on with the price of gas I used on the last tank when I filled up so its doing something right.

 

[Dave]

Its all about the terrain, the weather, and how you drive. Ive found my Jeep does the best this time of the year(in the spring and fall). Low humidity and lower temps really help it it seems.

If Im cruising down the hw at 55-65mph on flat, level ground, no wind, with the windows down, my scan guage will say Im getting 25mpg. As soon as I stop(stop and go traffic), go up a hill, pass someone, anything at all that includes giving it gas it will usually drop right down to 15mpg and even lower if it downshifts. Last night I was going up a fairly big hill in 3rd gear and it said 8.8mpg. It was having trouble holding 65mph and I was running 3500rpms(big hill).

I know the scan guage isnt 100% right but it gives me an idea of what Im getting. It was also dead on with the price of gas I used on the last tank when I filled up so its doing something right.

I think the scanguage is pretty accurate also. (maybe not 100% - but close) You can set the engine size and gas tank size etc to make it more specific to your vehicle and more accurate. I have the same experience with my scangague. It really shows you a significant difference in gas mileage and other readings on different terrain. Going up hill I will usually stay in the truck lane or center lane and if I start up at about 75 I can make the grade without the ****** shifting. (I don't usually drive that fast) Otherwise I just need to lock out od to be easier on the ****** and make the grade. Coming down is more fun though and gas mileage is unreal. Makes me want to drive down hill all the time.

So my mpg/scanguage experience is pretty similar to yours. My KJ likes 55-60 flat highway for the best fuel economy.

Dave

 

[VTNomad]

Electronic MPG calculators

The Scangauge II, EVIC and any/all other electronic mpg calculators all work in exactly the same way. They're not calculating any data, they just gather the data, and the calculations already done by your Jeep and display them for you.

MPG's are calculated from the mileage from your odometer and divided by the amount of fuel your injectors output. So accuracy depends on your how both your odometer and injectors are calibrated. Both can be affected by a number of variables, but they can get you in the ballpark.

 

[Smeltn]

I am getting around 18 or so, give or take. Granted 90% of my driving is Highway 50 miles a day back and forth to work.

 

[Dave]

I just finished changing my plugs and I might get 1 more mpg.....maybe. I'll see if it makes a difference this weekend.

Dave

 

[JeepJeepster]

MPG's are calculated from the mileage from your odometer and divided by the amount of fuel your injectors output. So accuracy depends on your how both your odometer and injectors are calibrated. Both can be affected by a number of variables, but they can get you in the ballpark.

Neat thing about the scan gauge is you can calibrate it independently from the jeeps speed-o.. I used 2 different GPS units to make sure it was dead on.