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Duramax 6600 Welcome to the Internet's first Duramax 6600 diesel discussion forum for the LB7, LLY, LBZ, LMM, LML, LGH & L5P RPO code engines. Tips on performance, fuel economy, troubleshooting and more.

View Poll Results: 2004.5 or newer LLY Duramax local driving fuel economy
less than 15 mpg (US gallons) (55-65-mph) 454 41.58%
15-16 mpg 163 14.93%
17-18 mpg 165 15.11%
19-20 or more mpg 220 20.15%
Don't own an LLY - just wanted to see poll data 90 8.24%
Voters: 1092. You may not vote on this poll

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  #1  
Old 12-31-2004, 02:27 PM
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Default 2004.5+ LLY Duramax Fuel Economy Poll

Fuel economy is one of the top 2-3 reasons why most people buy a diesel pickup.

What we want to do here is help determine what people are seeing for non-towing fuel economy in actual on-road use.

Let us know what your LLY Duramax powered 2500HD/3500 truck delivers.... This poll is for owners of the 2004.5 or newer LLY. We are assuming summer blend fuel.

You will need to vote before viewing the poll data. If you don't own an LLY, but would like to see the poll data, you'll need to first vote in the poll using the "Don't Own an LLY" selection for both the local driving and highway driving sections.

Round your fuel economy averages to the nearest whole number. For example a 16.4-mpg would be 16, a 16.8-mpg would be 17.

MP

[ 01-03-2005, 02:33 PM: Message edited by: More Power ]
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  #2  
Old 01-01-2005, 07:03 AM
Kennedy
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Here again, I voted a bracket down. I have seen 18.8 and 18.9 hwy, but couldn't justify the "push" to the 19-20 bracket. Not bad for only about 3k on the clock, and no bed cover yet!
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  #3  
Old 01-01-2005, 01:42 PM
DURA-MAX3 DURA-MAX3 is offline
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In 8800 miles mine is averaging 12 mpg. So far I am not impressed but it runs decent. I am going to put a chip on it and have fun. I figure if it gets poor mileage might as well make run like the wind.
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  #4  
Old 01-01-2005, 03:09 PM
J-M J-M is offline
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I voted but have a 4500. Alot heavier of a truck.
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  #5  
Old 01-02-2005, 05:41 AM
carco
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I wonder just how much a K2500 DA can pull?? I pulled 10000# yesterday 100 miles several hills WOW it pulls!! 8000# 38'gooseneck enclosed w/ 4 ATV's, 1 dirt bike, gear and 4 people. Southern Ohio, N Ky. hills, both sides of the Ohio river. I thought mileage would be 12-13 but was only 10.7 mpg for 104 mile round trip @ average 43 mph. A little disapointing for 17500gw, my C6500 w/ Cat 7.2L @ 10.88 mpg over 804 mile trip @ 68-72 mph to GRapids Mi. @ 20000#.
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  #6  
Old 01-02-2005, 08:58 AM
Cliffee Cliffee is offline
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I'm averaging 16.5 with mostly short city trips. 1800mi on OD. 2005 LLY
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  #7  
Old 01-02-2005, 02:29 PM
MPH MPH is offline
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I too have been a little dissapointed in the lly's mileage. driving home from the dealer it averaged 18.4, which I was impressed with, but it has never been that high since. Pulling a little two place snowmobile trailer, i was only seeing about 11 mpg. I put 305's on it right when i got it home. could this have affected it that much? It didn't seem to drop the LB7 that far.
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  #8  
Old 01-02-2005, 06:51 PM
HalsMax HalsMax is offline
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I just took a 400 mile trip. Averaged 19 cruising between 70-75. Programmed the Hypertech PP to stage 2 and she got 17 on the same trip, but was a lot more fun passing on two lanes. I have under 5K miles and am impressed with the mileage and pulling power. Gonna leave her on stage 2!!

[ 01-02-2005, 07:12 PM: Message edited by: HalsMax ]
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  #9  
Old 01-03-2005, 09:14 AM
Kennedy
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Having never owned a truck with an avg economy computer, (DIC) it has proven enlightening. While accuracy is sometimes not the greatest, and is really thrown off with many tuners/modules, it DOES give pretty good indication of what happens when you blast past csomeone or let the truck idle, or even drive off cold and the trans is in cold shift mode etc..

In order to get decent mpg you need to excercise restraint when passing, and minimize cold engine and idle operating time.
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  #10  
Old 01-03-2005, 07:57 PM
dcalex dcalex is offline
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You gotta be careful in looking at the percentage results on the poll....the question directed to the people who don't have a Dmax (which is the majority responding) is included in the percentages and it skews the results.

To date the percentages without the skewing question is this:

less than 15 mpg........5....11%
15 - 16.................14...30%
17 - 18.................17...37%
19 - 20.................10...22%

Thats 59% getting better than 17 mpg....not bad at all for that powerful an engine. [img]smile.gif[/img]
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  #11  
Old 05-11-2006, 10:01 PM
REDTRUCK05 REDTRUCK05 is offline
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Default Ugly

I own a 2005 2500 HD LT crew cab. MPG has been ugly since delivery. I average between 14 and 15 empty and if I am pulling my 5600# travel trailer, I get between 9 and 11
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  #12  
Old 05-12-2006, 07:47 AM
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rob from bc canada rob from bc canada is offline
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These poll results are definitely weird.

Has anyone ever pinned down a cause for those who experience such low mileage?

The numbers of them according to the is poll seems high enough to warrant a dedicated search for the problem.

Any mileage poll should show a bulge in the mid range, and not at both ends.

I drive for best mileage, and with the heavy 3500 4x4, I can reliably get a measured average of near 13 l/100 km (17.5-18 US mpg) driving 80% highway averaging 100kmh = 60 mph, 20% local, with a steep hill for 1.5 km up to my house at the end of each trip. That really cuts it down - it does burn 1-2 l coming upo that alone.

If I reset the computer on the highyway after it's warm, I can get down to 12l/100 = 19.6 mpg average over a 100 mile drive which is probably a bit optimistic. My DIC tends to be at least 1 mpg higher (.5 to 1 l/100k low)

With a high 3000 lb camper on, doing 100 on the highway consumption goes up to 18l/100 = 13 US mpg

These figures are not fantastic, but given the weight of the truck when compared to my old K2500 93 6.5 TD Standard shift which weighed about 1500 lbs less, seem more or less reasonable.

All this leads me to believe that either the poll results are off somehow, or a large number of the 05 LLY's have a significant problem, which could be fixed, because they can do better.
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  #13  
Old 05-12-2006, 09:44 AM
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The following two forum threads might help, both to explain fuel economy differences people see and to help troubleshoot a low MPG truck.

http://www.thedieselpageforums.com/t...ad.php?t=22302
http://www.thedieselpageforums.com/t...ead.php?t=9675

Jim
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  #14  
Old 05-15-2006, 06:00 AM
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16-17 MPG mixed 20 MPG highway at 1800 RPMS.
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  #15  
Old 10-24-2006, 04:23 PM
troyf63 troyf63 is offline
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Default Fuel mileage at highway speeds

I get between 19 and 21 MPG on the highway at 65 MPH. When I get on it though, it declines significantly. I really like the power when I can keep it out of the shop.
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  #16  
Old 10-26-2006, 07:27 AM
XTeam524 XTeam524 is offline
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Mine does good between 55-64 I can get around 18-20 depending on the day, but if I go any thing over 65 it goes down to 16 even 15. I think that is a bunch of crap. Why can a semi pulling 60,000lbs get 6-7 and my pick-up cant get 10 pulling a 40 enclosed trailer that only wheighs 7000lbs.
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  #17  
Old 07-01-2007, 06:08 PM
kantra kantra is offline
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Default milage

I have only 750 miles on miy 6.6 and it gets 15.2 per gallon and 11.4 towing my fifth wheel camper 13000lbs I figure that is not bad for an engine not even broken it yet
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  #18  
Old 07-07-2007, 12:15 PM
kantra kantra is offline
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Default strange

With 1000 miles on my truck I pulled my 14000lb fifth wheel home the other day not knowing the truck was in 4 high when I checked my milage it was 14.4. But in 2 wheel drive its only 11.3 what gives with this??
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  #19  
Old 09-29-2007, 12:53 AM
Chuck1 Chuck1 is offline
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Default 05 d max

I have been getting 20 to 22 mpg highway and with my 5th on 15 .Its only a 25footer and i can hardly tell its on there .Man I love this truck .I had a 6.5 before this for 10 years never had a problem did a few adds. thermestat high out put water pump and fan I never had it overheat and i live in some major mountians,I tow quite a bit flat deck trailers and my 5th but after reading about it here. I thought best to do the cooling mods. It was a good truck also when I sold it the buyer said what dosn't work on it ? It was a 94 and had a full load and I thought for a minute and realized every thing worked and had never given me a problem.It was a little slower up the hills than the dmax but a really good truck.If my 05 dmax treats me near as well I.ll be happy. And boy with the extra power and the heated seats I'm in heaven !
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  #20  
Old 01-08-2005, 01:41 PM
Lee_klm Lee_klm is offline
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I selected 19+ on Highway, but would need to qualify my answer as under 60mph driving. 70mph will keep me at 17, maybe 18 with the wind...
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