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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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More Power More Power is offline
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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 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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  #12  
Old 01-08-2005, 09:55 PM
belcll belcll is offline
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Quote:
Originally posted by MPH:
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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  #13  
Old 01-08-2005, 09:57 PM
belcll belcll is offline
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oops, did a false post. I added 285/75 tires and notice my mileage fall almost immediatly by about 1-2 mpg.


Quote:
Originally posted by MPH:
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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  #14  
Old 01-13-2005, 03:27 PM
Freeman777 Freeman777 is offline
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I participated in this survey (15 - 16 mpg city and 17 - 18 mpg hwy) a day or so after the poll was posted. I've been back several times since and noticed that the majority of the LLY owners fall into this category. I've been in the high 18's on several occasions, but didn't feel justified in voting in the 18 - 19 mpg class. Yesterday, on hwy #95 (just North of Las Vegas, NV) I ran a test under ideal conditions of road, wind, terrain, etc. and marked 20 miles at 70mph on the cruise control. The result was: 23.2 mpg according to my digital information center. My rig is a 2004.5 GMC C3500 CC, SLT, LB, 4WD D/A (LLY). After 6 mo. of use I now have 15K and the only thing I've been doing differently is using a fuel additive: Power Service -8 oz. per 25 gal. (states on the container: "absolutely no alcohol") Although this truck is running GREAT! I wasn't happy pulling a 36', 14+K, 5er over Baker grade (I-15 bet. Stateline, NV and Baker, CA) in 2nd gear, at 35mph at 3,500 rpm and both temp. gauges too close to hot for my comfort. Trips like that to San Diego resulted in 10mpg. Since my last trip, I've been anxious about the new Bank's set-up (in R&D for quite some time) for my LLY and got the GOOD NEWS call today: A six stage system (air filter, six-gun controller, exhaust system, boost and pyrometer gauges) that will selectively and progressively boost my engine/trans 128 HP and 345 fp torque. Stage #1 is the stock setting and every stage thereafter = a 20% boost. By going with the unique design of the Banks set-up, I think my engine/trans plus my 100,000 mi. after-market warranty will be better protected.
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  #15  
Old 01-17-2005, 04:01 PM
eagle in flight eagle in flight is offline
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My LLY has been getting about 18 mpg all by itself. When I tow a fifth wheel (weight around 14,000 pounds) and travel at 60 mph, I get around 11.5 mpg. Mileage is at 15,000.
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  #16  
Old 01-17-2005, 05:03 PM
fishhead1076
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At first very disapointed with the lly and fuel milage, my average was around 12 no matter what towing or mt. After 12K and first fuel filter change my milage changed drastically, went from avg. of 12 to 17 in the city and 18+ on the highway. Didnt really buy into the break in better fuel milage bit, but I must say I was suprised.

My 2 cents...
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  #17  
Old 01-23-2005, 04:01 PM
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Well just picked mine up last Monday night, did some round town back and forth to work running, then stretched its legs down to Virginia this weekend and the computer says 16.6mpg, not so bad running 70mph, Opps not supposed to go over 55mph in the first 500 miles, but ran well, didn't do any major acceleration's just cruised along with traffic. Should improve as it breaks in. First 100+ miles in stop and go driving, some high idle warm-ups. Will wait and see. Can't wait to hitch up and go.
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  #18  
Old 02-02-2005, 03:24 PM
jogger jogger is offline
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Did a short 150 mile round trip consisting of mostly freeway and rural driving and averaged 21MPG for that trip. In the city I average about 18.
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  #19  
Old 02-06-2005, 10:14 AM
guerrero guerrero is offline
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First 430 miles coming back from the dealer in Kellogg Idaho with outside temps hovering in the high 20's and several inches of snow on the ground through one of the mountain passes requiring prudent use of 4WD on I-90, averaged 20.5 mpg. Very happy with these results and expect additional improvements when I get the truck back to PH Hi and the warmer climates.
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  #20  
Old 02-06-2005, 08:30 PM
mjammer mjammer is offline
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I am seeing 17.1 for mixed driving on my new truck, 2500HD D/A 4WD CC LB (just picked it up Friday) in the first 200 miles. That is better than I ever saw on my old gas 2500 extended.
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