honest fuel mileage

LibertyCRD · **Posted:** Tue Jan 11, 2011 11:56 am

Joe Romas wrote:

My SPEEDOMETER error per my GPS is about 6% :lol:

But my GPS as far as I can tell does not have a "miles traveled" function so I'm not sure how accurate (inaccurate) the ODOMETER is :juggle:

Liberty,
One mph at what speed? If it's at highway speed yours is the most accurate anyone has mentioned in over 4 years I've been reading here. Most with stock tires report the speedo giving a 6% high reading. For example a 59 speedo reading times .94 gives you 55.46 mph that matches the rounded 55 my GPS indicates.

My first CRD (bought new) was PERFECT on the speedo and odo (GPS verified). This CRD was about 2% off and is now 2% off the other direction since I went with taller tires. My wife's '04 3.7L KJ was also right on the money. I'm surprised there are people with factory tires and everything that are 6% off at the speedo. This seems like something that the manufacturer would be required to fix if it was really that bad. 6% is a little ridiculous. I would have never allowed that to fly on one of my rigs.

tjkj2002 · **Posted:** Tue Jan 11, 2011 12:26 pm

LibertyCRD wrote:

Joe Romas wrote:

My SPEEDOMETER error per my GPS is about 6% :lol:

But my GPS as far as I can tell does not have a "miles traveled" function so I'm not sure how accurate (inaccurate) the ODOMETER is :juggle:

Liberty,
One mph at what speed? If it's at highway speed yours is the most accurate anyone has mentioned in over 4 years I've been reading here. Most with stock tires report the speedo giving a 6% high reading. For example a 59 speedo reading times .94 gives you 55.46 mph that matches the rounded 55 my GPS indicates.

My first CRD (bought new) was PERFECT on the speedo and odo (GPS verified). This CRD was about 2% off and is now 2% off the other direction since I went with taller tires. My wife's '04 3.7L KJ was also right on the money. I'm surprised there are people with factory tires and everything that are 6% off at the speedo. This seems like something that the manufacturer would be required to fix if it was really that bad. 6% is a little ridiculous. I would have never allowed that to fly on one of my rigs.

+/-5% difference is the industry standard.Only vehicles that are outfitted for police duty have certified calibrated speedo's.

equipt31 · **Joined:** Thu Jul 08, 2010 5:02 pm **Posts:** 27

Before I cleaned my MAP sensor I can only verify i was able to do 25mpg on the highway for a whole tank, did about 70 (had to go faster in MI, 70 in the slow lane is not enough lol) and ran the A/C on low.
Did some maintenance and cleaning but unfortunately it's winter now so w/the new blend of diesel and alot of 4wd'ing I have been getting as low as under 20 in all-street driving. Def looking forward to the summer but it sure beats my ex-4runner in the same conditions

obthomas · **Joined:** Tue Nov 30, 2010 2:29 pm **Posts:** 28

Mo 06 spedometer is about 5 mph faster than I am really going. Tested with GPS and neighborhood speed radars subtract 5 mph from what I see on the spedometer.

This being said my everyday short trip around town milage is between 22 and 23 mpg tank after tank. My mods are: EHM, clean MAP, and GDE Ecotune. :BANANA:

papaindigo · **Posted:** Wed Jan 12, 2011 7:40 am

Correction factor based on GPS distance (two 50 mile tests) that is 1.73% more than od. so actual mileage is 1.0173 x od mileage with factory tires at 50% or less tread left in contrast to stoutdog who has the same size Michelins with essentially 100% tread. Variation in rolling distance between tire brands of the same nominal size can be significant in the long run as can variation due to tread wear. As to actual hand calculated and corrected mileage - stock 2005 pre-GDE Eco tune 17-20 average 19 in town vs. 27-28 hwy; post-GDE Eco tune 22-23 town (drop to 20-21 with bad tstat) vs. solid 32 for 2,000 mile hwy trip (see
http://www.greendieselengineering.com/f ... st/32.page) although I suspect my tstat gave out on that last tank now that I look back at performance.

VAdave · **Posted:** Thu Jan 13, 2011 6:13 pm

During the winter I get 22mpg during mostly highway miles with 31x10.5 mud tires and steel wheels, also have a GDE eco tune.. Just got the new tires and wheels in December so I haven't seen the difference in fuel blends yet. Before new tires and wheels i was getting upper 20's during the summer.

paulevans76 · **Posted:** Thu Jan 13, 2011 7:14 pm

With a 2" lift and 31's I got as good as 28.5 mpg on a highway trip, trying to keep the rpms (and therefore speed) as low as possible while maintaining my own sanity. With the 32's I recently got 24 mpg in some fluctuating elevation on the highway, while keeping the cruising speed down around 72-73 mph (puts me just under 2k rpm). One the way home, I only got 20 since I was going closer to 80 mph. The further under 2k you can keep it, the better, from my experience. In town I get 16-20 depending on how much of a hurry I'm in.

I don't have any engine mods aside from the map disconnect, elephant hose, aftermarket muffler of some sort, and no trans mods. Can't wait to see what I can get with a stronger torque converter and ECM and TCM tunes.

Collingwood · **Joined:** Sat May 01, 2010 9:53 am **Posts:** 24

Has anyone drove long distance at a steady 55 MPH with the GDE TCM and Eco full torque tune and with stock or 215/85-16 highway or all season tires in 5th (I know you can't do this with the F37 Chrysler TCM tune)? I would like to know what is the maxium MPG you can get on flat ground in 5th with a locked TC. I haven't been about to find this info on the GDE website. What is your MPG when you are going as slow as you can go and stay in 5th locked with the GDE TCM with Eco full torque? I hope GDE will answer these quesitions.

Roostre · **Joined:** Sun Oct 24, 2010 3:57 pm **Posts:** 195

Collingwood wrote:

Has anyone drove long distance at a steady 55 MPH with the GDE TCM and Eco full torque tune and with stock or 215/85-16 highway or all season tires in 5th (I know you can't do this with the F37 Chrysler TCM tune)? I would like to know what is the maxium MPG you can get on flat ground in 5th with a locked TC. I haven't been about to find this info on the GDE website. What is your MPG when you are going as slow as you can go and stay in 5th locked with the GDE TCM with Eco full torque? I hope GDE will answer these quesitions.

I can tell you that even at 33.5 on the EVIC, it will continue to climb when you hold a steady 55 mph. Since my EVIC is usually 4-5 high, I would guess that the approximate max is over 28-29 mpg.
:2cents:

stoutdog · **Posted:** Thu Jan 13, 2011 9:56 pm

Collingwood wrote:

Has anyone drove long distance at a steady 55 MPH with the GDE TCM and Eco full torque tune and with stock or 215/85-16 highway or all season tires in 5th (I know you can't do this with the F37 Chrysler TCM tune)? I would like to know what is the maxium MPG you can get on flat ground in 5th with a locked TC. I haven't been about to find this info on the GDE website. What is your MPG when you are going as slow as you can go and stay in 5th locked with the GDE TCM with Eco full torque? I hope GDE will answer these quesitions.

I got 35.4mpg doing 60 in those conditions. Didn't have the TCM tune yet, so 60 was about the lowest I could go.

CATCRD · **Posted:** Thu Jan 13, 2011 10:59 pm

With the TCM tune you can stay locked in 5th at 48mph on flat ground. I don't have the patience to go a half or a whole tank at that speed and measure true mpg.

ROCK! · **Joined:** Sat Dec 18, 2010 3:38 pm **Posts:** 156

Stock with the MAF unplugged, doesn't get much more honest then a pic.

fastRob · **Posted:** Sat Jan 22, 2011 11:39 pm

My worst ever was 19mpg, best was 29mpg.
I might try to go 60 but I love to blast the Green Diesel Hot Flash. Love the rattle.
Most highway is ~75mph and I get 24-25mpg with strong turbo spools out of the toll booths.
I also use 2 stroke and Grey diesel additive when I remember.
Do not overfill the oil, just put in what is specified and check the dipstick, mark it. (or is that off topic?)

stoutdog · **Posted:** Sun Jan 23, 2011 10:28 am

ROCK! wrote:

Stock with the MAF unplugged, doesn't get much more honest then a pic.

Actually, it does. The EVIC, even on stock CRDs, is often 3-4mpg high. You need to measure how much fuel you put in against how many GPS miles you've driven.

ROCK! · **Joined:** Sat Dec 18, 2010 3:38 pm **Posts:** 156

I do, and as soon as this tank is gone I'll come back with my actual numbers. I was pretty impressed with that though, driving a brick at 75 and getting 30MPG. It may be high, we'll see in a few days. I also should note that Im using premium diesel from chief petroleum. It's a bit more expensive, but much better then the "gas station" ULS!

stoutdog · **Posted:** Sun Jan 23, 2011 2:47 pm

ROCK! wrote:

I do, and as soon as this tank is gone I'll come back with my actual numbers. I was pretty impressed with that though, driving a brick at 75 and getting 30MPG. It may be high, we'll see in a few days. I also should note that Im using premium diesel from chief petroleum. It's a bit more expensive, but much better then the "gas station" ULS!

Full stock, my guess is you are closer to 25-26 at that speed. It's been a long time since I had the stock ECM, but I believe the EVIC always had a tendency to keep climbing on prolonged highway trips.

Post-tune, I drove 450 miles nonstop once. Every 10 miles, the EVIC climbed 0.1mpg. By the end of the drive, it said I was getting something around 44mpg! The tune exaggerated the issue, but I vaguely recall something similar occurring before.

geordi · **Posted:** Sun Jan 23, 2011 6:36 pm

Against my Garmin, I know that my odometer reads low by somewhere around 7-9 miles per hundred. I use the GPS and try to fill to the very very top of the fuel neck, (called "venting" in the VW circles) but it seems that the pumps are more and more just dispensing FOAM. Ridiculous.

Last time I ran a full tank tho, (still with the stock failing thermostat) with the GDE Eco Tune and Transmission tune, no EGR, No cat, 2.5" exhaust, EHM, NO LIFT, 215/85/16 BFG Load Range D tires at 60psi... 26mpg COMBINED, about 60% hwy for this tank.

I haven't had a highway-only tank where I'm not in a decent push to get somewhere OR towing, so I don't have HWY only miles to point at. But those highway miles are all at about 70-75 mph. I have a decent amount of "city" driving where I'm doing 10 mile stretches at about 60mph, and I try to avoid any hard accelerations at all times. But putting your foot into it sometimes is just fun. Where I do think I lose a bit is on one particular bridge that I have to take to go into Savannah or back home - Easily a 10-12 percent grade, and it is a half-mile climb. Steep bridge.

onthehunt · **Posted:** Sun Jan 23, 2011 11:35 pm

With a small lift and E range tires:

18-21 City Winter
22-25 Highway winter
Add two MPG with summer fuel. If you fill and drive the whole tank on the interstate below 73mph add another 1-2 MPG.

JeepJeep · **Joined:** Fri Aug 28, 2009 12:54 pm **Posts:** 2

Honest fuel mileage...isn't that an oxymoron?

I have an essentially stock 2006 Liberty CRD.

Using the mileage computer’s estimate but adjusted for the speedo inaccuracy (speedo reads 60, GPS reads 57), I routinely average 27 mpg in combined city and highway driving.

At just highway speeds at 70 mph, I hang right at 30 mpg.

Also, fyi, my best mileage is at about 45 mph (31-32 mpg), even though I’m not in top gear and the TC isn’t locked at that speed (so wind resistance really starts to make a difference at faster speeds).

One other note, surprising to me my mileage has consistently measured higher by about 2 mpg after changing the fuel filter (no other changes and the improvement has lasted for more than 3 months so far). The old filter may have been really clogged. Considering the cost of the fuel filter verses fuel prices, cost wise it’s worth changing the fuel filter at every oil change (if one always regains 2 mpg). Have to get more data points...

Oh yes, also I live in Texas on the Gulf Coast, so most of the driving around here is across flatland (the only hills around here are called overpasses).

grsjax · **Joined:** Sun Oct 03, 2010 7:26 pm **Posts:** 61

I just got the GDE Eco-Tune and results are very good. I am getting about 24mpg mixed city/highway driving. About 22 around town and 28 on the highway.

honest fuel mileage

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