2004.5+ LLY Duramax Fuel Economy Poll

[REDTRUCK05]

I own a 2005 2500 HD LT crew cab. MPG has been ugly since delivery. I average between 14 and 15 empty and if I am pulling my 5600# travel trailer, I get between 9 and 11

[rob from bc canada]

These poll results are definitely weird.

Has anyone ever pinned down a cause for those who experience such low mileage?

The numbers of them according to the is poll seems high enough to warrant a dedicated search for the problem.

Any mileage poll should show a bulge in the mid range, and not at both ends.

I drive for best mileage, and with the heavy 3500 4x4, I can reliably get a measured average of near 13 l/100 km (17.5-18 US mpg) driving 80% highway averaging 100kmh = 60 mph, 20% local, with a steep hill for 1.5 km up to my house at the end of each trip. That really cuts it down - it does burn 1-2 l coming upo that alone.

If I reset the computer on the highyway after it's warm, I can get down to 12l/100 = 19.6 mpg average over a 100 mile drive which is probably a bit optimistic. My DIC tends to be at least 1 mpg higher (.5 to 1 l/100k low)

With a high 3000 lb camper on, doing 100 on the highway consumption goes up to 18l/100 = 13 US mpg

These figures are not fantastic, but given the weight of the truck when compared to my old K2500 93 6.5 TD Standard shift which weighed about 1500 lbs less, seem more or less reasonable.

All this leads me to believe that either the poll results are off somehow, or a large number of the 05 LLY's have a significant problem, which could be fixed, because they can do better.

[More Power]

The following two forum threads might help, both to explain fuel economy differences people see and to help troubleshoot a low MPG truck.

http://www.thedieselpageforums.com/t...ad.php?t=22302
http://www.thedieselpageforums.com/t...ead.php?t=9675

Jim

[USA-1]

16-17 MPG mixed 20 MPG highway at 1800 RPMS.
USA-1

[troyf63]

I get between 19 and 21 MPG on the highway at 65 MPH. When I get on it though, it declines significantly. I really like the power when I can keep it out of the shop.

[XTeam524]

Mine does good between 55-64 I can get around 18-20 depending on the day, but if I go any thing over 65 it goes down to 16 even 15. I think that is a bunch of crap. Why can a semi pulling 60,000lbs get 6-7 and my pick-up cant get 10 pulling a 40 enclosed trailer that only wheighs 7000lbs.

[kantra]

I have only 750 miles on miy 6.6 and it gets 15.2 per gallon and 11.4 towing my fifth wheel camper 13000lbs I figure that is not bad for an engine not even broken it yet

[kantra]

With 1000 miles on my truck I pulled my 14000lb fifth wheel home the other day not knowing the truck was in 4 high when I checked my milage it was 14.4. But in 2 wheel drive its only 11.3 what gives with this??

[Chuck1]

I have been getting 20 to 22 mpg highway and with my 5th on 15 .Its only a 25footer and i can hardly tell its on there .Man I love this truck .I had a 6.5 before this for 10 years never had a problem did a few adds. thermestat high out put water pump and fan I never had it overheat and i live in some major mountians,I tow quite a bit flat deck trailers and my 5th but after reading about it here. I thought best to do the cooling mods. It was a good truck also when I sold it the buyer said what dosn't work on it ? It was a 94 and had a full load and I thought for a minute and realized every thing worked and had never given me a problem.It was a little slower up the hills than the dmax but a really good truck.If my 05 dmax treats me near as well I.ll be happy. And boy with the extra power and the heated seats I'm in heaven !

[Lee_klm]

I selected 19+ on Highway, but would need to qualify my answer as under 60mph driving. 70mph will keep me at 17, maybe 18 with the wind...