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lml duramax mileage?

gonefishin

gonefishin

1/2 ton status
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Location
Carthage tx
So after my quest for a used dmax i ended up buying a new 2015 z71 ltz crew cab. I have 1300 miles on it and have just drove 300 miles all highway and only got 17.5 mpg. Thats the best i havegot on any of the 4 tanks. What is everyone getting for milage on these? I was expecting at least 20 on the highway. I pulled my boat around for 1 tank and only got 12 mpg. Its only 3200 lbs including the trailer. I am totally disappointed with the fuel mileage. Any advice on what to do? I really don't want to void the warranty with a tune .
 
Unfortunately with all the emissions, that's probably all its going to do.
 
The fuel mileage will improve some once it is broken in. This is common. My 2015 6.0 is in the same boat with only 800 miles on it so far.
 
I don't have any personal experience on this but the pre 'emissions' d-maxes got better mileage. 2007 and older.
 
My 2014 got similar mileage for the first couple thousand miles. It gets closer to 20mpg on the highway unloaded and 16mpg towing 12k lbs now
 
There are two kinds of diesel owners, those who don't get as great of fuel economy, and liars. You were suckered in by the latter group.......

Martin
 
I have a 2011 LML, bone stock, 50K miles. It has gotten about 21mpg on an unloaded road trip with the cruise set at about 75. Commuting...15-17mpg. Everybody loves the LBZs. They're good motors, but the trucks they are in are nowhere near as good as the newer body style(s) as far as build quality and frame/suspension strength. Also, they came stock with about 150 lb-ft LESS torque than the LML. The advantage is they have no emissions junk and are easily tuneable. The LML is not easily tuned (emissions, encrypted computer, etc), but is, as far as I'm concerned, a great package stock.

I say break it in and give it some time. The mpg will improve slightly, but don't expect tanks to average in the 20s. High teens are realistic depending on your driving and all in all, its a damn good truck.
 
My 2014 LML CCSB got around 17mpg for the first 20k. For the last 5k or so I'm seeing it climb to the high 18's and low 19's. 90% of my miles are freeway at 70 to 75. Towing is around 15-16.
 
I think your going to have a hard time getting 20 MPG out of most diesels. I know everyone has that truck, or a buddy with it that gets 24 MPG driving 95 MPH into a head wind while towing 25,000#.

In my 05' with power added, exhaust, 285/70/17 tires, leveled, head studs, home made intake etc. I'm lucky to see 18 HWY and 14 daily driving. I can easily get as low as 9 towing but if I take it a bit easy I get 10-11 towing 10,000#+.

You should see a small increase once the truck is broken in around 20,000 miles but it will easily decrease with any mods, tires etc.
 
Dad's '04 gets about 18-20MPG unloaded, unmodified. His driving style does not lend itself to good gas mileage though. I suspect it could be 1-2 higher.
 
Its not hard at all with a real tune, not a canned POS.

LMM - Dips under 20mpg at 80 MPH

11071515_367182330135527_4770432265431681299_n-L.jpg


LLY - Hits 22 at sustained 75 MPH.

11081499_367065670147193_5869695592991784689_n-L.jpg


LBZ with stock gears and 37s. I don't have a picture of it but it was still 17 mpg wide open at 110 mph.

11753686_422076777979415_4676154087360947280_n-L.jpg


11063815_422076767979416_4773143506092599138_n-L.jpg


Are they slow after a real tune. Nope. Everyone I tune gets the speedo corrected by GPS.

LMM above on mileage tune. CLICK
 
Team208Motorsports said:
Its not hard at all with a real tune, not a canned POS.

LMM - Dips under 20mpg at 80 MPH

11071515_367182330135527_4770432265431681299_n-L.jpg


LLY - Hits 22 at sustained 75 MPH.

11081499_367065670147193_5869695592991784689_n-L.jpg


LBZ with stock gears and 37s. I don't have a picture of it but it was still 17 mpg wide open at 110 mph.

11753686_422076777979415_4676154087360947280_n-L.jpg


11063815_422076767979416_4773143506092599138_n-L.jpg


Are they slow after a real tune. Nope. Everyone I tune gets the speedo corrected by GPS.

LMM above on mileage tune. CLICK
Click to expand...

Nice to see you on here as well, had no idea you were a ck5 guy!

-shawn
 
miniwally said:
I think your going to have a hard time getting 20 MPG out of most diesels. I know everyone has that truck, or a buddy with it that gets 24 MPG driving 95 MPH into a head wind while towing 25,000#.
Click to expand...
Exactly.....

Try running a diesel in the real world and see what actual mileage is. Best I can do with my Dodges is 14-15 in town, 17-18 on the freeway, 10 while towing lightweight (10K) and 8mpg when towing heavy (24K). My 7.3 PSD's.... forget it... my F450 that weighs 14K on it's own gets about 10mpg with no trailer.... my F350 does slightly better.

Oh and BTW, mileage is calculated when you fill the tank and divide miles by gallons used, not a dash readout. :whistle:
 
When I hauled bulk seed this past spring with a Powerstroke, I couldn't get the dash readout over 7 mpg.......

Martin
 
82355 said:
When I hauled bulk seed this past spring with a powerstroke, I couldn't get the dash readout over 7 mpg.......

Martin
Click to expand...
There was your problem. :doah: I'm not a big fan of them, the 6.no and 6.4 are junk, the new 6.7's are good, and the old 7.3's are good for the most part, but just don't stack up to the cummins of that same late 90's era. I bought two OBS PSD's because they are cheap these days and it beats having anything gas powered around.
 
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