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Why does the 3.7 Liberty's MPG suck so bad ??
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=51&t=1134		 Page 3 of 5
Author:  ManicMechanicJoe [ Fri Dec 30, 2005 8:37 pm ]
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The wieght is an issue but on the highway, our main downfall is aerodynamics and gearing. Above 50 mph 55% (i have seen figures as high as 70%) of our power is used to overcome windforce. So a more aerodynamic shape would help any vehicle. Having low gears (the majority of us run 3.73 which is very low for this size vehicle) keep our engines revving high off road and on. The lower you can keep your RPM's, the better gas mileage you will get. Low weight will help city mileage as you are accelerating less mass but it won't help on the highway provided you are cruising at a constant speed. You want better mileage? Buy a diesel. Too much money you say? get higher gears. Then stip out all of your interior, get a free flowing exhaust and K&N FIPK. Then you might get 25 on the highway. I like my seats and low gears though.
Author:  benmar2000 [ Fri Dec 30, 2005 9:50 pm ]
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All I am going to say is.. IT IS A JEEP!! You don't buy a Jeep for it's economy factor.. You buy a Jeep for it's fun factor... I knew that I wouldn't get that great of a gas mileage when I bought my Jeep... So I bought it.. If I wanted economy.. I would have suggested the wife to buy another Saturn or a Honda or something...

By the way.. If you want to talk about driving a brick.. Drive a CJ or a YJ or a TJ... Those are truly Bricks on 4 wheels..

Ben
Author:  OBX KJ [ Wed Jan 04, 2006 5:59 pm ]
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Dont forget that the rolling resistance of your tires makes a huge difference.
Look at Tirerack.com under the Goodyear Silent Armors customer ratings. These guys are quoting some drastic decreases, even with staying with an OE size.
Author:  retmil46 [ Sat Jan 07, 2006 1:47 pm ]
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Guys, if you wouldn't mind a suggestion from the diesel side of the house...

Both the CRD and the V6 use the EXACT SAME STOCK MUFFLER! It's necked down to 2" on the inlet and outlet, and baffled out the wazoo.

If you check under the CRD section of the forum, you can see where us diesel guys have been replacing this stock POS with Flowmaster 40's, Magnaflows, Aero Turbines, $12 cherry bomb glass packs, and some even going straight pipe. and the reported increase has been anywhere from 2 to 3.5 MPG in all cases.

One gent went with a Flowmaster 40 aluminum version, less than $100 installed, and picked up 2 MPG. Another went with a Magnaflow Hushpower II and picked up 3.5 MPG. I went with an Aero Turbine 2525 and by my hand calculations picked up around 3 MPG combined.

Don't know if you would see similar gains with the V6, but for less than $100 for a Flowmaster, might be worth a try.
Author:  auggy [ Sun Jan 08, 2006 11:43 pm ]
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InCommando wrote:
The Liberty is kinda a porker. It weighs about what a 1/2 ton truck weighs, and gets mileage like one...


Except that it weighs 2 tons .. :?
Author:  l337fpc [ Fri Jan 20, 2006 9:05 pm ]
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I was wondering, if the key to good highway gas milage is to keep the engine's RMPs relatively low; is there a significant difference between an '02 libby with a automatic tranny and an '02 libby with a manual tranny?

I know that having only 4 gears in my automatic libby causes my libby to guzzel gas when going over 75mph (mainly 75mph-90mph). If i was driving a libby that has a manual tranny and was doing 75-90 in the 5th gear, would I get significantly better gas milage compaired to my automatic libby?
Author:  Eddo [ Fri Jan 20, 2006 10:20 pm ]
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l337fpc wrote:
I was wondering, if the key to good highway gas milage is to keep the engine's RMPs relatively low; is there a significant difference between an '02 libby with a automatic tranny and an '02 libby with a manual tranny?

I know that having only 4 gears in my automatic libby causes my libby to guzzel gas when going over 75mph (mainly 75mph-90mph). If i was driving a libby that has a manual tranny and was doing 75-90 in the 5th gear, would I get significantly better gas milage compaired to my automatic libby?


I doubt it. Going over 75mph in a brick will kill gas mileage. At fast highway speed the greatest lose is air drag. Air drag increases by your speed squared. For example going from 50mph to 75mph air drag increase 125%. Or a whopping 300% from 50 to 100(not that you should go 100)
Author:  jp41kj [ Sun Apr 09, 2006 3:54 am ]
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My brother works for Chrysler in the Transmission plant that makes the kj tranny. His info is that the tranny is part of the problem with the poor mileage. This may be just plant gossip but you never know. Better mileage on road could also effect offroad capabilty. If it cann't go offroad, it's not a Jeep.
Author:  Stuhlie [ Fri Jun 02, 2006 1:45 am ]
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This is my 1st jeep ever which is LIBBY .With my driving I'm getting about 16.5 this came from a full tank of gas to
when the gas lite came on and I refilled it with 15.8 gallons . Now I have added 4ozs of acetone to the next tank to see what
happens !! My Other truck that I traded in on this Libby was F150 xcab 5.4 L Triton and it about 14mpg
Author:  DarbyWalters [ Wed Jun 07, 2006 4:04 pm ]
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Before I traded in my 2002 3.7L for a 2006 CRD I did some extensive rpm mileage tests. The KJ with Auto got the best mileage (highway) at 2125-2175 rpm...I think that was around 68 mph.
Author:  chetos [ Tue Jun 13, 2006 9:14 am ]
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I did a 240 mile round trip yesterday. I got 16.6 MPG. That was with AC on and off at times but doing around 80 MPH. I am gonna try that "keep it under 2000 RPM's" thing. It's gonna be hard because I have lead perminately attached to my foot.
Author:  cahreh2003 [ Mon Aug 21, 2006 5:02 pm ]
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Hi all im new here.I have a 2006 Liberty it has 1000 miles on it. I get 15mpg.Mixed city and up hill driving.
Author:  kolesy [ Tue Aug 22, 2006 2:00 am ]
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cahreh2003



Schuylkill Co. baby!!! Love my coal region! :D
Author:  warblade666 [ Tue Aug 22, 2006 2:19 am ]
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My brother was making fun of my Jeeps today because his...

'78 Blazer K5 with a 400ci v-8 on 35" tires!!
gets 15-16mpg city/ 20-22mpg highway.

and yes, the speedo/odom is correct.

Both Jeeps get about 12-13 city/ 17-18 highway.

He can't understand why the mileage is so bad on our newer "small" suv's.
Author:  corwyyn [ Tue Aug 22, 2006 2:48 am ]
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chetos wrote:
I did a 240 mile round trip yesterday. I got 16.6 MPG. That was with AC on and off at times but doing around 80 MPH. I am gonna try that "keep it under 2000 RPM's" thing. It's gonna be hard because I have lead perminately attached to my foot.

I drove from Phoenix to Albuquerque and back this past weekend. I didn't have a chance to keep track of the milage going up but coming back I went 417.7 miles (according to my GPS, odometer reading was 412.3 total) and used 16.56 gallons of gas for an average of 25.2 miles/gal. Some of the things I tried on this trip were 1) kept speed down - on the freeway I set the cruise control to 70mph which translated to 2100rpm on the tachometer, 2) ran my tires at 38psi to lower rolling resistance, 3) I was able to run with the a/c off most of the way, so I'm sure that helped a bit. On most of my previous trips I was able to avg around 22mpg running 75mph on the freeway with a/c on, but this time I wanted to see just how much I could squeeze out of the Liberty and I was plesantly surprised :D Oh, and I have a K&N filter but I have no idea how much the contributed.
Author:  Guest [ Mon Jul 09, 2007 11:30 pm ]
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The problem is that DC didn't put a big enough engine in it with taller gears. a 4.7 V8 and 3.55 (or 3.2x?) gears would have yielded just enough sack for the liberty, yet it'd pull better numbers for gas mileage.

Think about it...a Hemi Charger or 300 gets close to 30 mpg on the highway. my last T-bird ('88 5.0L with a mild cam and an AOD and 3.27 gears) got 29-31 on roadtrips with an EIGHTY-FIVE MILE PER HOUR AVERAGE!

More motor, steeper gear=gas mileage. I want a 500 cadillac in mine with a 2.50 ratio in each pumpkin :lol:

Granted, weight=rolling resistance, and aerodynamics all come into play...but a bigger engine and a steeper gear ratio would HELP. Just the steeper ratio would be good, but then you'd be driving a sackless vehicle...the Liberty's guts come from the 3.73 (or whatever they are) gears. Granted, y'all with load range E tires ain't gettin any help either:P
Author:  jdorris [ Tue Jul 10, 2007 12:45 am ]
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My 72 Commando gets about 8-10 in town and 14-16 highway, so I am pretty happy with the crd's mileage 21-23 in town, 26-27 highway.
I do have a heavy foot.
Now if I can keep it out of the dealership...
Author:  M&P40 [ Thu Aug 23, 2007 2:15 am ]
Post subject:  5600 lbs ???
am i the only one who has a liberty with the sticker on the door listing the GVW at 5600 lbs? it is a gasser renegade
Author:  KJ4ME [ Fri Aug 24, 2007 11:58 pm ]
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19.87 MPG! a little less than half of the tank was highway and the rest was all city.
Author:  Guest [ Sat Aug 25, 2007 3:24 am ]
Post subject:  Re: 5600 lbs ???
M&P40 wrote:
am i the only one who has a liberty with the sticker on the door listing the GVW at 5600 lbs? it is a gasser renegade


that's GROSS vehicle weight rating. that's everything INSIDE the KJ, passengers and cargo. yours weighs more like 4300 or so.
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