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Discussion Starter #1
I got a 08 chev duramax long box with the large fuel cell 140L I think, this thing stinks for milage at best i'm averaging 650kms to a tank, just put in 130L and got 640km's. I bitch about it everytime the truck goes in for service and they tell me they can't do anything. They told me it gets better in time, BS!!! I got 30 000 kms on it now and sure has not got better. Sure not like my 2002 duramax.

So I'm wondering what people are doing to get better milage out of this thing being the dealer is not helping me?
 

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I got a 08 chev duramax long box with the large fuel cell 140L I think, this thing stinks for milage at best i'm averaging 650kms to a tank, just put in 130L and got 640km's. I bitch about it everytime the truck goes in for service and they tell me they can't do anything. They told me it gets better in time, BS!!! I got 30 000 kms on it now and sure has not got better. Sure not like my 2002 duramax.

So I'm wondering what people are doing to get better milage out of this thing being the dealer is not helping me?
I have a 2009 3500 4x4 GMC. My first mileage check came out as follows. 780km. driven. 100 Litres filled it right to the top. My math tells me that's about 21 mpg.:D

That being said, I drive with a big foot,that's half the reason I bought a Duramax! On this particular trip I know of three times I had the speed governor cut in so it truly was'nt being driven for fuel economy.

That kind of tells me that your truck has something wrong! Go to another dealer and try talking to someone who has a clue about your truck.
 

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Is your truck stock? tires, lift, exhaust? what is the rear gear ratio? I have found a big difference in the trucks with 373 and 410s.
 

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I have a 2009 3500 4x4 GMC. My first mileage check came out as follows. 780km. driven. 100 Litres filled it right to the top. My math tells me that's about 21 mpg.:D

That being said, I drive with a big foot,that's half the reason I bought a Duramax! On this particular trip I know of three times I had the speed governor cut in so it truly was'nt being driven for fuel economy.

That kind of tells me that your truck has something wrong! Go to another dealer and try talking to someone who has a clue about your truck.
Hmmm I have an 08 LMM and I can not get ay where close to 780kms a tank empty, stock with the wind blowing up my ass. You can get it driving over 140kms/h. I have not heard of a stock LMM getting any where near 21mpg stock.

People are doing the DPF delete to help with mileage but te warrenty goes out the window. My dealer is taking pic of the exhaust system when you come in for service as well as checking for any programers. Any warrenty work and they take a snap shot of your ECM and send it in before the work is done.

How many clicks you got on your truck? I heard that after 75,000 kms they start to get better mileage. I can get 17mpg incase you are wondering.

Later
Phil
 

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That trip was when my truck only had 2000 km on it. Driving fro Fort St John back to Houston. It's pretty much an eight hour trip and I had just finished my job in FSJ and was finally getting home.
I drive pretty hard and those figures are exactly as stated. I am not like some who might change things around for whatever reason.
If my truck was shitty on fuel I would state that too! I have found a couple things about the truck to be kind of disappointing but fuel mileage and power have been good so far.
The truck being light might help,it's a regular cab. Can't wait for some tuning just for the extra balls. I was just in Grande Prairie a couple weeks back.
Saw Reba at the Crystal Center! She was great........weather was crappy though!
 

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Well I don't know how many km's are versus miles, but since the day I got mine I have gotten 15.3mpg. Got in it this morning and noticed it had dropped to 14.3 mpg.
 

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Coleman didn't say your mileage was out but I think it is calculated to just over 18, not 21 that is all. I lived in FSJ for 9 months here a couple of years back, i take it you are in the patch are ya? I know a salesman for an oil tool company and he gets 19 mpg with a 09, CC LB hauling up to 3000 LBS but that is 110 kms no more.

Later
Phil
 

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before I put the rims and tires on I got 21mpg on the interstate from Virginia to south carolina. I have the 373 gears though. With the new tires and rims I still get 16mpg on the interstate.
 

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Discussion Starter #12
My 08 3500 is bone stock, with my work camper on it. Most of my driving is city like not straight highway. 10 to 15 mins into Vernon than off to the job sites witch are about 15 min to 30 mins mostly. I think even when I didn't have the work camper on I was only getting avr. 18L to a 100kms.
 

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Phil you were probably using U.S. gallon for the calculation. Here is the math I used. Bear with me and you can double check this for yourself.

1 imperial gallon =4.54 lt.-----100 lt=21.996 gallons.
1 mile=1.609 km.----------------780km=484.67 miles
484.67 miles divided by 21.996 gallons=22.034 MPG.:D

Now I am not saying I drove 140kph and got that mileage but going through the Pine Pass and a couple other places she was wide open passing slow poke etc!
 

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Why are you using imperial gallons? I think our D max's are calculated in US gallons = 3.875 Liters or 20% less that the imperial so LOL 22.034 - 20% = 17.6MPG... Now I am currious.

Does anyone know for sure if the D max is calculated with the US gallon on the DIC?

Later
Phil
 

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Phil. I used imperial gallons in the equation because that's what we buy in Canada. American trucks show lower mpg due to the smaller U.S. gallon.
I don't care what that dic says about mileage as it has been proven to be unreliable. Hand calculated is what matters as those figure do not lie.
 

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I dont recall the exact # of kms but i made in one trip home with the 09 it was around 800 km ( I have a long box) I got 20.75 MPG Canadian. 1 gallon being 4.54 liters.
I havent bothered to check since then. I now have 6000 km on her.
PS thats at about 110km per hour
 

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I think theres a lot of confusion regarding how far a person can go on a tank caused by the two different sizes of tanks available. Long box vs shortbox.
Youngone your 09 and mine are really close as far as mpg goes. Someone only getting 640km on a tank is not unusual with a shortbox truck. Driving for 15 minutes at a time sure won't help either! I hope mine gets better yet but it seems alright now and really I could probably do better just by driving differently. It really does not mean all that much to me. At least it's not a 6 ltr.pos getting 13 mpg.
 

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before i got the set up i have now i had a full banks pack on it stil have the intercooler, intake, but now it runs the ppe hot+2 before when i had the six gun i could get 24mpg with the dpf at 70mph now 19 is my average with no dpf towing
 
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