Duramax MPG

rebel_horseman

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Depends on gears and whether your truck came with that DPF garbage that the LMM has. If you've got the 4.10s then I would agree with what was said above. If you have the 3.73s then I would think about 2mpg better.
 

TLBREWER

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Scott

My truck ('06 LBZ) is a SRW so it has 3.73's. Unladen except for me, wife, and dogs, If I set the cruise at 65 I get 22-23MPG. No engine mods. Just put my MBRP 4" cat-back on this week so I'll be curious if it has any effect. Sure sounds better.

Tom
 

MJ Synthetics

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Its my understanding that all Duramax/Allison combos come with 3.73 gears in the rear end. Can anybody confirm that?

I used to get 16 combined empty in my LLY. I now get 19 combined 21-23 hwy and mid 10's towing my 11k lb trailer.
 

rebel_horseman

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In the 2500HD trucks, the Dmax/Allison combo is only available with the 3.73s (unless something has changed recently.) In the 3500 trucks 4.10s are optional. In the Kodiak 4500 and up trucks you can get deeper gears (4.30s I think).
 

TLBREWER

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In the 2500HD trucks, the Dmax/Allison combo is only available with the 3.73s (unless something has changed recently.) In the 3500 trucks 4.10s are optional. In the Kodiak 4500 and up trucks you can get deeper gears (4.30s I think).

I was thinking the duallies came standard with 4.10's. Optional in the SRW's, which are standard 3.73's (3500's that is). I do know my 3500 with 3.73's has plenty of zip off the line and gets pretty decent mileage for what it is.;Sweet

Tom
 

82fordtruck

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I was thinking the duallies came standard with 4.10's. Optional in the SRW's, which are standard 3.73's (3500's that is). I do know my 3500 with 3.73's has plenty of zip off the line and gets pretty decent mileage for what it is.;Sweet

Tom

I think they all had 3.73.
I just drove 1400 miles - 80 mph ave with a big crate in the bed that stuck above the cab a foot.

14.2mpg.
 

Dixon Peer

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My '09 Duramax gets 15.5 mostly around town mpg (some highway) and for strictly highway driving, 22 mpg. Not bad for pushing almost 7000 lbs around.
 

tbirdfiend281

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those mileages seem low.

I was tracking mine on paper using the trip odo, regular odo and the gallons at the pump, when the pump would click off, filling slowly also. I had a 01 LB7 RC LB 4x4. Edge box, ppe wastegate bias, exhaust cut off at the cab,and a deep sump trans pan, on some 32s (265/75R16 all terrains comes out to a 32.2" tall tire.). I would run mine around mostly on 1, because anything higher the trans wasnt liking it, and I was getting 16-17 in town, and on the highway around 19-20 on average, and I use to cruise usually around 75-80mph. I took her to SC to get my Z and got 24mpg going down unloaded with me and some cloths, coming back up with the z in tow on a uhaul trailer I got 16mpg cruising at 60-65mph

p.s. the variations between the trip odo and the regular odo where never more then 5 miles. I had to be sure.
 
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