LMM mpg?

[SmallFish]

You must have been doing 65MPH. My 08 GMC 2500 has gotten as high as 22 driving granny style for short spans on the highway. But an actual long drive (200-300 miles) over interstate driving at no more than 70 MPH I have had as high as 20.2 unloaded. Of course the wife was nagging at me the whole time because I was driving so slow. Driving normally at 75-80 it gets 16-18 MPG. It all depends on how much I'm liking the turbo that day and how much the other drivers are pissing me off.

Around town it gets 14 if I stay off the turbo.

Hurricane Fay busted out a window and I had the dealer reflash the ECM (recall) and check out the rear diff while it was in there. They put me in a gasser 2500 rental Chevy. That beast was getting just over 11 on the highway. I refused to keep it and traded it in for an Envoy.

Pulling a 4,000 lb boat, my 04 Chevy 1500 gasser got 7 MPG on the highway @ 65 MPH and frequently downshifted to 2nd to clear overpasses. The LMM gets 12 @ 75 MPH and the Allison never downshifts. We have a winner. (Just hit 10,000 on the odometer.)

BTW - All these number came from the DIC. Whenever I hand calculate, the numbers are within 1 MPG so that's close enough for me to skip the math without guilt...

[whawa]

Yea I was driving between 68 and 70 the whole time. Had the cruise set right below 70.

[tshideler]

i still only get 15 empty around town@ 8,000 miles on it, no hotrodding on it. I am running a little heavier than stock w/ front and rear bumpers and dually also toolbox in bed may cut mine down some.

[gmessina]

I am using the Bully Dog Power Pup programmer. I had it programmed for "performance" and went on a 200 mile trip. On the trip over I got 20.4 mpg. Before starting back I reprogrammed for the "tow/econ". I got 19.4 mpg. However, it seems my in-town mpg is way up compared to the performance mode. When I got to work this morning, it was on 18.

Jerry

[glwbear]

My truck was a dealer trade from Oklahoma to SC. My mileage sucks and I get 11.2 to 12.6 mpg! All this smog crap and the CAT & the PF are killing these trucks. When it goes into regen there is extra fuel poured into the motor to help make the PF get as hot as a Blast Furnace so it burns away all the soot.

I wish I had done more research and bought me a truck from Canada or a 2007 without the PF.

I put a Banks Son of a Gun tuner with the PDA and I installed my own cold air package. My 2002 Duramax had the CAT removed before I bought it and with an EDGE attitude in only the "Drive Mode" would blow the doors off my 2008.

How are we going to get away from foreign oil if each year the cars & trucks they produce use more & more fuel because of the smog regulations?

NOW figure this one out..... if the PF in the REGEN mode is using more fuel to complete the regen process isn't that burning more fuel and releasing more hydro-carbons into the air? I mean if you use fuel to burn the soot it's still all going into the atmosphere????

If they would design a more fuel efficient diesel we might not be faced with having all the added on devices that choke the shit out of our trucks and give us terrible mileage. Did you know that the EPA give all government and Police and emergency vehicles an exemption from having any pollution devices on their vehicles. I know this as a fact as when I was a Police Officer all of our undercover and Patrol vehicles were exempted and never had to have any smog testing. Now is that fair?

glwbear
"Not to happy with my smogged to death 2008"

[Billfish]

Drove to Jacksonville, FL via I10 East from Mobile, AL. This is almost as flat and straight as an interstate can get. Driving right at 70mph I was getting (hand calculated) 18mpg. For the whole trip with some local stop and go and two lane highway in heavy traffic I got an overall average of 17.5mpg.

Truck had right at 1000 miles to start and finished with about 2150. I don't think it is completely broken in yet so I am still fluctuating the rpms every 5 or 10 minutes. With a few 1000 more miles I'm thinking it will get a bit better. Hoping for around 20 mpg at interstate speeds of 70.

[Killerbee]

Winter sees a lot of rports of reduced economy, most will say it's the different fuel BTU value. Mainly its the fact that the Dmax is very difficult to warm up, taking as much as 20 miles before decent efficiency is reached. It is a pig under 100 F ECT.

My suggestion is USE your cold front cover, and make sure the truck is plugged in and warm before you leave. For commuting you will probably see a 2 mpg increase with these techniques alone, perhaps more if your commute is less than 10 miles.

I usually only read these threads for a laugh. MPG is #2 as far as ego truth stretching, you can guess what #1 is.

Another idea I came up with recently: replacing the low temp stat with a flat blank. This will increase engine temp 20 degrees. But it reduces cooling system capacity, so it is mainly for non-towing applications.

[x2desmit]

2007 with 16000 miles now...16 in the city...22 to 24.5 on the interstate at 65-67 MPH. Yes, that's a slow speed.

[LMMnewbie]

13.5 mpg empty with 80% on the hwy 20% in town... both cases using a light foot to see what I can get for mileage. There is about 2500 miles on the truck so far, and the mileage test was only done over the 200 miles since I bought it last week. I was fooling around tonight testing an Edge chip and running a few quarter miles and my mileage was 9mpg over the 17 miles I accumulated during the testing. All of this info is from the DIC and most of the time with a full 55 gallon tank. (the previous owner replaced the stock tank with the larger aftermarket tank) I am in Edmonton Canada right now and the temp has been around 32F (0C) during this testing. The diesel sold here is much thinner during the winter season and I was told by my bulk dealer that it has approximately 18% less btu per pound than the summer fuel sold here. I have driven several Dodge diesels for about 200,000 miles in the past and have not noticed a reduction in power during the winter fuel season. Also this truck is a crewcab dually with Toyo Open Country tires.
I am amazed at the wide variations in mileage within this thread and have to wonder if some of the good mileage #s we are seeing are from drivers in the far south whom are using our equivalent of summer fuel. I also wonder if my truck would be more efficient at 180* + since it is only running at 170 now. I will try a winterfront and much more accurate tests as I travel south into warmer climates and regions that sell thicker diesel.

[Jfarmer]

Before cold weather hit, 19 mpg local driving, 14 mpg with 7K lb trailer. Didn't even check with the fifth wheel, just stopped at every other fuel spot.