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Unread 10-23-2009, 09:27 PM   #1
jeepmanalex
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v8 vs Inline 6 Gas milage

Hey guys I don't mean to beat a dead horse but I'm just trying to get as much input as I can as to the gas milage between the two different engines offered in the 99-04 GC's. I just got rid of my tj and I know the old inline 6 is a great motor but it just doesn't compare to the v8 when it comes to power and smoothness. My dad is pushing me to get another 6 cylinder because he is worried about gas milage with the v8. From what I have heard there isnt a whole lot of difference and for the extra power its worth it, but at the same time it is hard to find v8's with the part time 4wd system instead of the awd system which would seemingly take more gas. Any thoughts or experience here would be greatly appreciated!

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Unread 10-23-2009, 09:31 PM   #2
gatorayde
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There is maybe a .5 mpg difference. Get the V8; more power for the heavy WJ's and hardly any difference in gas mileage.
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Unread 10-23-2009, 09:36 PM   #3
Max78
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My 02 is getting 19.6mpg 40/60 city/highway
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Unread 10-23-2009, 09:59 PM   #4
aintnothang
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I get about 21.4 on highway.
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Unread 10-24-2009, 01:34 AM   #5
befumo
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Yeah get the V8 in WJ. Those 4.7s are really nice.
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Unread 10-24-2009, 03:12 AM   #6
ratmonkey
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Some people can squeeze a few extra mpg from the i6. The v8 will tend towards 18 in mostly highway driving in stock form.
There is practically no mileage difference with the part time case compared to the awd case. All the same junk is always causing rotational drag in the driveline with both systems.
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Unread 10-24-2009, 04:58 AM   #7
Turbonut
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Always enjoy reading mileage threads, but hvaen't seen any posted with the 24MPG as of yet. I guess it's early.
Although the EPA ratings are not etched in stone, at least they afford comparisons, so if Dad is concerned with fuel mileage, have him look at the EPA fuel mileage site. Only recommendation I can give is to make certain the Jeep is a '01 or newer as that has the 5 speed AT. It is said that teh '99/'00 can be reflashed to add the 5th gear, but have no experience at this.
As was stated in your other thread, the AWD (which is an on damand system, not AWD) system uses no more fuel than the 242.
Here's a couple of examples:

2002 Jeep Grand Cherokee 4WD
Jeep Grand Cherokee 4WD 6 cyl, 4 L, Automatic 4-spd, Regular 13 city 18 hwy
Jeep Grand Cherokee 4WD 8 cyl, 4.7 L, Automatic 5-spd, Regular 12 city 17 hwy

2004 Jeep Grand Cherokee 4WD
Jeep Grand Cherokee 4WD 6 cyl, 4 L, Automatic 4-spd, Regular 14 city 19 hwy
Jeep Grand Cherokee 4WD 8 cyl, 4.7 L, Automatic 5-spd, Regular 14 city 19 hwy

To sum it up, you'll find no difference in mileage with the QT/QD/242 systems in a particular model.

Don't know who will be paying for the Jeep, but I'd be more concerned with the cost of repairs then to the fuel mileage. You'll find that the WJ's, with mileage are money pits, and stay away from the AZC Limiteds/Overlands, unless you're willing to spend $1200 to fix the system, or you can do the work yourself. Look for a Laredo 4.7 with QTII and you'll be good to go, but you're still looking at window regulators, radiator, starter, HP PS hose, maybe already replaced, heated seats that are broken, and depending on the area of country, pay particular attention to oil pan rust and also under carriage rust. The pans are paper thin and won't hold up to much rust, so if bubbles have started a new pan will be in the future. Good luck.

Last edited by Turbonut; 10-24-2009 at 05:17 AM..
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Unread 10-24-2009, 07:46 AM   #8
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I'll put it this way. My 2004 QuadCab Ram 1500 with the 4.7L averages 14MPG right now. My ZJ with the 4.0L averages about 14.5MPG right now. Enough said.
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Unread 10-24-2009, 09:24 AM   #9
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I drove a 2004 2WD 4.0 for about six months and the computer said it got 15mpg. I bought a 2002 Overland all time 4WD 4.7L H.O. about six months ago and the computer says 18mpg. Both of theese Jeeps are all stock, the 4.7 will get worse mileage if I race it around everywhere I go but it's well worth the extra power IMO. Try for a 4.7L H.O.
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Unread 10-24-2009, 09:30 AM   #10
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When I looked, the 4.0 was rated at 19 highway, and the 4.7 was rated at 20 highway. Don't ask me how that works. The plus you get with the 4.slow is its legendary reliability and it is...well...relatively easy to work on.
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Unread 10-24-2009, 09:30 AM   #11
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i have an overland i thought they had an extra overdrive gear. i can get 24mpg if i do 55. but 20-22 is more like normal highway driving while doing 65-70. over 70 though and it sucks fuel
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Unread 10-24-2009, 09:31 AM   #12
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Quote:
Originally Posted by C-note View Post
I drove a 2004 2WD 4.0 for about six months and the computer said it got 15mpg. I bought a 2002 Overland all time 4WD 4.7L H.O. about six months ago and the computer says 18mpg. Both of theese Jeeps are all stock, the 4.7 will get worse mileage if I race it around everywhere I go but it's well worth the extra power IMO. Try for a 4.7L H.O.
Don't go by the computer, do the calculations yourself.

As most have said, both get comparable MPGs. I don't have any first hand experience, but from what I've read on these forums it seems like the 4.0 and 4.7 get about the same. With that said, go with the 4.7 and you won't regret it
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Unread 10-24-2009, 09:38 AM   #13
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I had a '98 dodge ram 5.9L got me like 12mpg a little more it was awful and $80 to fill. My I6 zj gets an 18.2 avg. If I really want to i'll buy another Honda and get 30-40mpg
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Unread 10-24-2009, 01:33 PM   #14
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If you are pretty easy on the 4.0 you can get decent fuel economy. For instance, about two weeks ago I drove down to Harrisonburg, VA (about 250 miles), and got about 22.5 mpg, which was a little less than I normally get with my ZJ on the highway since I was going faster than usual. On the way back I took it easy varying between 55 and 65mph on the highway, while drafting trucks the whole way. By the time I got off the highway, my VIC was reading 26.5mpg, and by the time I was done driving through towns and hitting hilly backroads to my house I was at 26.1mpg. My VIC is usually fairly accurate when I did measure it, however occasionally it has been a little high (.5mpg or so).
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Unread 10-24-2009, 02:20 PM   #15
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Originally Posted by 1941Galant View Post
If you are pretty easy on the 4.0 you can get decent fuel economy. For instance, about two weeks ago I drove down to Harrisonburg, VA (about 250 miles), and got about 22.5 mpg, which was a little less than I normally get with my ZJ on the highway since I was going faster than usual. On the way back I took it easy varying between 55 and 65mph on the highway, while drafting trucks the whole way. By the time I got off the highway, my VIC was reading 26.5mpg, and by the time I was done driving through towns and hitting hilly backroads to my house I was at 26.1mpg. My VIC is usually fairly accurate when I did measure it, however occasionally it has been a little high (.5mpg or so).
If you can get 26 MPG in a Jeep, write to the car manufacturers and tell them your secret.
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