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Discussion Starter #1
Wife and I drove the round trip from Phoenix to Tucson on Monday. Fueled at the Flying J on I-10 in Eloy for $1.61 per gallon. Mileage from Flying J, driving in Tucson, and then refilling at the J on the return to Phoenix was 18.6 mpg. That mileage was with the ac on and four people in the truck. Wife drove about three-fourths of the trip and she has a heavy foot.
 

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According to my fuel gauge, 177.5 miles at 3/4 tank, I'm getting over 27mpg!!



Sure would be nice if GM wou
ld put in an accurate gauge and sender!!!Edited by: Oldman
 

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$1.61 in Eloy is still a lot lower than in the Valley, huh? Sounds like your mileage is about right for that kind of trip. I drive a minimum of 5 mph over the limit most places and your mileage is pretty close to mine. Gotta love driving a beast that gets mileage like a mid-size car!
 

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It would be nice to see some of the mileage claims that people make..


(I am NOT calling anyone a liar here!)


But all I heard before I bought my dmax was that they get 20mpg after the first 10k. That is empty highway miles.


Well I get 13.5-15(high) with mixed hwy/city driving.


Then I only get 16/17 on the highway running about 8 over the speed limit.


I now have 20k on the truck. I was just hoping for a little more..


And if this is all I have to gripe about with my truck then I say I am doing just fine..
 

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Hey Lonewolf, my claim above was nothing but sarcastic. I hate the cheap gauge/sending unit they put in these trucks. I was serious about having 177.5 miles and the gauge only dropping 1/4 . However, I know it's going to drop like a rock from this point on. My actual mileage is around 17 to 17.5. That's 80 miles per day, 40 of it is between 60 and 80 dpending on traffic. The rest is back roads at anywhere from 25 to 50 mph.
 

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Most people who claim that their Dmax gets 21 mpg are right - when they're feathering it at 60mph with no headwind... lol

I have 38,000 fully documented miles (spreadsheet) that my '03 GMC CC/LB D/A has put on. I am averaging 18.1 according to my spreadsheet, and 17.9 according to the DIC.

I get about 14.5 hauling, & I can get over 21 on the freeway in cruise as long as I stay below 70mph. My average around town seems to be about 16.5.

I've heard about lower mpg Dmaxes & don't know why they get less than mine. Probably driving style.
 

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Just took my first half-a**ed trip with the truck....280 miles round trip....hit a bunch of traffic so there was a lot of stop and go, and fuel gauge is now reading 1/2 tank. DIC is still showing a range of another 214 miles, which sounds about right. Truck has 2k miles on it, bone stock, trip was made empty, nothing in tow. If my calculations are right, that works out to @19mpg.
DIC showed the same during the trip.
 

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i've owned my jimmy about 10 weeks...about 10 days after i adopted it a friend of mine and i made a trip trip new jersey, with about 39k on it...it was mostly interstate driving...my calculations showed that my mpg was a little over 16...i thot that was ok, but i was a little disappointed, as i thot i mite get more like 18mpg...


the truck rode VERY nicely and i love it...NOTWITHSTANDING that it's getting new injectors today with 41k on it
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Discussion Starter #9
If an Dauramax owner, whose truck is under warranty, feels that the vehicle is not giving the mileage it should, might be able to get the dealer to connect an analyzer to the computer. The truck must be driven while connected to the analyzer. We had our Duramax tested with a five ton trailer behind on a six percent grade on I-17 in Arizona. According to the analyzer, we now have 97% efficiency, which gave us between 13-14 miles(average) per gallon on continous hills and grades on the interstate southward from Flagstaff. Non-towing on I-10 between Phoenix and Tucson yielded 18.6 on Monday. The mileage and diesel fuel price was posted earlier today on this website. Trying to find a dealer who is willing to make this test was not easy. It took nearly two months to find a cooperating dealer. My wife was ready to trade but now has changed her mind.
 

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On a recent 900 mile (in one day) trip to Kentucky and back I recorded this mileage: Cruise set on 65 average mpg = 18mpg, cruise set on 75 or so, 21 mpg. From previous trips, 55mph gets me 23 mpg. This is for real mileage, this '04 doesn't have as much squirt as the '02 that it replaced. Oh yea I forgot to mention, the truck has 13K on it.Edited by: zsqure
 

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Wow worth the trip to Eloy just for a fill up...


Tucson is at $1.79 at the cheap stations...





cmc
 

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I have no clue why but my dads old 01 dmax dually never got over 15 mpg. It got 9 pulling 11.5 empty around town and if he was lucky he could get 15 on the highway. He drives very easy and never gets on the gas. Could never figure it out.
 

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I am hearing alot about cheap gauges in the Duramax Diesels but I want to report that on my way home from work I decided to test my fuel systems computer. I was running on empty and the warning light had already popped on with the chime and I was showing 38 miles left to empty. I pulled into the fueling station and the gauge read well below empty and the tank took 24 gallons exactly without topping off. The owners manual indicates I have a 26 gallon tank and the computer was reporting an average of 19 miles per gallon. (I commute 50 miles round trip each day all freeway.) My point is the computer is right on the money so don't look at your gauge just keep the miles to empty displayed in the driver information window and you should never run out of fuel.


Love my Duramax so far!
 

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just ran my first tank of fuel through since i purchased my 2002 silverado, all local mileage. back and fourth to work. I got 15.88
 

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'02 2500 HD D/A ext cab 2WD

June '03 43,000k 3400.1 mi round trip CA/Montana/CA traveling with wife, kayaking & camping gear w/15' double kayak on overhead rack; 70-75+ mph much of the way; no trailer hitch, fill into filler neck 1st & last = 19.3 mpg.


Feb '04 49,000k CA/Salem, OR, 426.2 measured miles on I5, towing 21' TT approx 6500# @ avg speed 55-60mph on cruise, + 5th whl hitch, no passengers = 15.3mpg.

Mar '04 return Salem, OR/CA, I5, 531.7 measured miles no trailer @ 67 - 70 mph (2000 - 2050 rpm on cruise) + 5th whl hitch no passengers = 19.7 mpg
and any time I "needed" to pass anything at 80+ mph did it but prob 95% @ 2000rpm.


Total mis including in-between running around Salem, OR and trip to Vancouver, WA and back to Salem : 1328.1 mis for trip average of 17.3 mpg
 

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duramax dan said:
... My point is the computer is right on the money so don't look at your gauge just keep the miles to empty displayed in the driver information window and you should never run out of fuel.

Hard to do if your truck doesn't have that function!!
 

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2004cc lb7 sb 2wd..19combo driveing, about 50/50 highway,in town. Trip to myrtle beach 21.70, 75mph. I am very pleased Edited by: BRUCE
 

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<TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNABLE="off"> My first long trip to Maine ( round trip = 350 miles) , yielded 22 mpg.
This was 95% highway, with cruise set at 68 or so. I believe if I babied it without cruise on, I could get 24 highway. Love watching the instant mileage readout!!! Great way to realize max mpg. cruising speeds, especially on back roads. 45 mph seems to work great in o.d. gear, a bit tricky keeping it there though, as it likes to downshift near that speed with slight incline.</TD></TR>
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I just checked my first tank of fuel on my 04 GMC CC 4x4 3500 LLY DMAX/ALLISON. 13.9. About 1/2 town 1/2 highway. I don't know what the dic said, it's usally not close, so I don't bother. I have a little iver 300 miles on it.


Al.
 
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