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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: LB7 Duramax local driving fuel economy (55-65 mph)
less than 15 mpg (US gallons) (55-65-mph) 97 7.79%
15-16 mpg 251 20.16%
17-18 mpg 337 27.07%
19-20 or more mpg 376 30.20%
Don't own an LB7 - just interested in the poll data 184 14.78%
Voters: 1245. You may not vote on this poll

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Old 02-26-2013, 04:22 PM
Dustdevil1 Dustdevil1 is offline
Join Date: Feb 2013
Location: Huntington Beach, California
Posts: 18

I often pull a trailer weighing around 10k lbs. Under those conditions, I typically see 10mpg while climbing from sea level to the Mojave Desert (around 2800 ft). 16 mpg on the way home. 13 mpg on flat freeway.

Without the trailer, I see about 16 combined, and about 21 on the highway. But I usually drive past 70 mph. Fuel mileage varies dramatically with rpm on my truck. I would imagine it does with all of them. I have 3.73:1 axles, and it's a 4X4 with oversized tires. I'm sure that has a little something to do with it. Plus, I don't often specifically drive for fuel mileage.
2003 Dmax Crew Cab 4X4 LS
Nicktane 2micron Cat Fuel Filter
A commercial shell and a Trucklocker
That's it.
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Old 09-19-2015, 03:28 AM
Dek Hawkins Dek Hawkins is offline
Join Date: May 2008
Posts: 50
Smile Dek Hawkins

I have a 2500 HD DMAX, 2002, and drive it in England.
I can say it does 27mpg on a 100 mile motorway trip @ 70-80mph,
or 22mpg dodging around.
I know many 4x4 owners who get less from their 2.0L diesels.
I would never swap it. I want a fifth wheel camper to haul, but need to get one from States ??
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Old 11-25-2015, 06:19 PM
Ian7 Ian7 is offline
'04 Silverado 3500
Join Date: Nov 2014
Location: Savannah, GA
Posts: 31

Originally Posted by Dek Hawkins View Post
I have a 2500 HD DMAX, 2002, ... it does 27mpg on a 100 mile motorway trip @ 70-80mph,
Given how far from 'typical' that number is, may I ask if that was a single 100 mile trip and tank top-up when you got there? I guess what I'm saying is that the top-up may have shut off very early and given a false economy?

or maybe a 100 mile long downhill stretch? :-)

(yes I know imperial vs US gallon, still 24+ in our context)
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Old 01-19-2016, 02:50 PM
chessy56 chessy56 is offline
Join Date: Jan 2006
Location: South Milwaukee, WI
Posts: 230
Smile '01 LB7 economy

Without a head wind, running ~57-60mph, mostly empty bed, I'm doing about 22-23 mpg on the highway. Depending on the severity of the head wind, I'm around 19 highway. Most trips are WI to mid IN.

Currently, I'm not getting Chit- truck appears to be down with head gasket issue. 400,700 on the odometer. Sure would like to upgrade to something newer, but a drop in fuel mileage would blow....

What's funny is watching the 50 mile average fuel economy with my Edge monitor plugged into the diagnostic port. Going through Chicago (I-94/I-294 with the sound barriers/trees/buildings blocking most wind), the Edge reported as much as 50 mpg! Bite me! Calculated value and not real, I realize. Still amuzing to watch.
So. Milwaukee, WI
'01 2500HD, LB7, 440K miles
"Stock" engine. Dual fuel filtration system with Kennedy lift pump, BF Goodrich Commercial T/A Traction tires (sold to a dude from Texas- it's living a warmer life just fine down there now!).

'17 2500HD, L5P (Happy Birthday/Merry Christmas to me!!!) Currently bone stock, 90K miles.

"Socialism is a philosophy of failure, the creed of ignorance and
the gospel of envy. Its inherent virtue is the equal sharing of misery."
Winston Churchill
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