Fuel mileage?

[okiejoe]

just purchased a new to me Chevrolet Duramax 6.6 with the Allison automatic, just driving it around town yesterday running some errands it shows average fuel mileage at 10.6, what do you think. I think it's still breaking in. It's a 2013 with 55900 on it I previously had a dodge cummins that got about 12 mpg up until about 75k then it began to go up to 19 around town and 12 to 13 pulling my 5er. Never had a Duramax before.

[Last_Train]

We've logged just over 5,600 miles over the last 1 1/2 years towing our Coachmen Freedom Express 192RBS with our 2011 Honda Ridgeline RTL. Hand calculated mileage is 9.02. That covers trips from SE Texas to the Ozark Mountains and multiple trips to Texas Hill Country and rolling terrain in deep East Texas' "Big Thicket."

[S_Davis]

You should be able to reset to zero, then it will start recalculating currant overall fuel mileage.

[trail-explorer]

okiejoe wrote:
but not sure how long it takes to calculate again

It doesn't calculate at intervals, it's a running total and changes "on the fly"

[trail-explorer]

okiejoe wrote:
...just driving it around town yesterday running some errands it shows average fuel mileage at 10.6, what do you think. I think it's still breaking in.

It's done breaking in.

Fuel mileage won't likely improve much as it ages.

DIC mpg readout on the dash for daily driving running errands is not 100% accurate, nor is it a good indication of what highway towing mileage will be.

[N-Trouble]

ktmrfs wrote:
First, if it going through a regen cycle, and your in town, yup you could be down to 10 or less. But the big thing is what is the mileage over a full tank.

Now, if you use the remote start to warm it up, do lots of short trips, and it's winter, don't expect great mileage. And depends on what your "town" driving really is.

On my 04.5 and on my 2015.5, I figure 13 ish around town. sometimes more, sometimes less. But then your "town" drive cycle could be better or worse than mine.

^^THIS^^

[N-Trouble]

okiejoe wrote:
just purchased a new to me Chevrolet Duramax 6.6 with the Allison automatic, just driving it around town yesterday running some errands it shows average fuel mileage at 10.6, what do you think. I think it's still breaking in. It's a 2013 with 55900 on it I previously had a dodge cummins that got about 12 mpg up until about 75k then it began to go up to 19 around town and 12 to 13 pulling my 5er. Never had a Duramax before.

19 around town??? Come on... Is that a one stoplight town?

[S_Davis]

I get between 13-14mpg @ 10,600lbs hauling a commercial canopy on the truck.

[Jayco-noslide]

With that no. miles I think its broken in. 10 sounds too low to me. My half-ton gasser did 12-13 in town.

[Second_Chance]

When I used mine for the daily work commute (average speed of about 35 MPH), it got about 14 or 15. On the highway not towing, about 19. Now it just gets used to pull our 13,400 lb fifth wheel - has been averaging 11 - 11.5 since getting some tire and alignment problems straightened out with the trailer. Prior to getting the trailer fixed it was getting about 10.5 MPH coast-to-coast.

Rob

[ktmrfs]

First, if it going through a regen cycle, and your in town, yup you could be down to 10 or less. But the big thing is what is the mileage over a full tank.

Now, if you use the remote start to warm it up, do lots of short trips, and it's winter, don't expect great mileage. And depends on what your "town" driving really is.

On my 04.5 and on my 2015.5, I figure 13 ish around town. sometimes more, sometimes less. But then your "town" drive cycle could be better or worse than mine.

[allen8106]

I have a 2013 GMC with that same engine & tranny, I calculate my mileage every fill up. I do very little city driving but get 10+ towing and 16-17 not towing.

[MinnCamper]

10 in town is bad. Even here in Minnesota I get 16 in town . Alot of idle time brrrrrrrr.??

[DutchmenSport]

Mine is a 3500 6.6 Duramax (dully). Mine seems to be all over the charts depending on the type of driving. Towing I get 10 mpg very consistently. Not towing it bounces around between 11 and 17. It has everything to do with how much you come to a complete stop and then have to overcome inertia to get moving again. The more complete dead stops you experience, the worse the fuel mileage will be. The bigger the engine, the more noticeable this is too. This is why, when driving my truck, I do all I can to avoid complete 100% stops, and try to work the stop lights so I never have to come to a "complete" stop when in town. It doesn't always happen, but I try. I have found the direct relationship between dead stop - starts and rolling stops.

FYI, I found my best fuel mileage is interstate driving at 65 mph (not towing) on flat ground (Like between Indianapolis and St. Louis, Mo, or Indianapolis to Columbus, OH). Towing, my max mpg is about 57 mph. (so 60 towing is my sweet spot).

In the mountains, it will drop to 9.9 towing. That's the lowest I've ever calculated. My truck just turned over 30,000 miles.

[okiejoe]

I agree, 10 mpg is bad but I think it's because it's been on the car lot and only had test drives and idled a lot which will lower mileage but not sure how long it takes to calculate again