Fuel Milage

[E.W.]

Have a 2008 GMC Sierra crew cab long bed, milage isn't to bad until the regeneration cycle starts. Are their any kits or programers that can bypasss this. I went with diesel this time for better milage i am disapointed. I asked every one I saw at the gas station who had a diesel truck for 2 years about their milage and problems, from the info I gathered the GM trucks were the best. For milage I heard between 16 to 18 around town and from 20 to 26 on the highway. I am lucky if I get 15, when the regen kicks on my reading on the average economy read out will drop 1.5 to 2 miles per gallon. The regen cycle happens once per tank, except for the latest tank full it has done it twice and I am at 12.9 mpg average. I have almost 6000 miles on the truck and I dont have a heavy foot and use cruise control when ever possible.

[wolowic1]

What kind of weather do you live in? I live north of Chicago and have a 2001 crew cab, short bed, 4x4 and the mileage will drop 1-2 mpg in the winter due to cold and winter blend fuel. Friction from snow and sloppy roads is a minus as well. I find myself always around 15 in the decent weather, but 13 to 14 in winter. Highway mileage I have yet to top 20 mpg running 70 mph plus with an unloaded stock truck. Personally I question the calculations of those claiming much over 20 mpg highway. With winter blend fuel my highway mileage is 17 to 18 mpg. I touched 20 mpg only a couple times running open 2 lane roads never exceeding 55 mph really babying the truck. When I bought the truck diesel was actually always running cheaper than gasoline, but now that's not the case so the cost advantage isn't really there if just looking at fuel costs alone.

[E.W.]

What kind of weather do you live in? I live north of Chicago and have a 2001 crew cab, short bed, 4x4 and the mileage will drop 1-2 mpg in the winter due to cold and winter blend fuel. Friction from snow and sloppy roads is a minus as well. I find myself always around 15 in the decent weather, but 13 to 14 in winter. Highway mileage I have yet to top 20 mpg running 70 mph plus with an unloaded stock truck. Personally I question the calculations of those claiming much over 20 mpg highway. With winter blend fuel my highway mileage is 17 to 18 mpg. I touched 20 mpg only a couple times running open 2 lane roads never exceeding 55 mph really babying the truck. When I bought the truck diesel was actually always running cheaper than gasoline, but now that's not the case so the cost advantage isn't really there if just looking at fuel costs alone.
I live in Maryland, haven't driven in the snow, and I baby the truck. This regeneration system on these new trucks stinks, wish I had bought a 2006 before the EPA passed the new emission laws. If the truck didn't have this i would probably average 17 or 18 mpg.

[Kennedy]

It might help to get the truck out and work it a bit. The DPF can be removed and DTC's turned off, but that's legal for off road use only ;)

[E.W.]

It might help to get the truck out and work it a bit. The DPF can be removed and DTC's turned off, but that's legal for off road use only ;)
How would anyone no you didn't have it unless you told them? Is there anything else that would help the milage.

[Hook_'em_Horns!]

How would anyone no you didn't have it unless you told them?

Visually during a State Inspection.

[E.W.]

Visually during a State Inspection.
Yes, but I am not going to have it inspected, it is only required when you sell the vehicle in Maryland.

[mr. monte]

if you take it in for warranty work, it could lead to some issues

[Dakster]

My mileage doesn't change by the season. We always have summer blend fuel here in South Florida. However, when I go up north, whether it is in the winter or summer my mileage always increases. I guess eve my city driving on vacation is easier than my normal city driving.

Regens REALLY stink and make my mileage plummet too.

[E.W.]

My mileage doesn't change by the season. We always have summer blend fuel here in South Florida. However, when I go up north, whether it is in the winter or summer my mileage always increases. I guess eve my city driving on vacation is easier than my normal city driving.

Regens REALLY stink and make my mileage plummet too.
What kind of milage do you get?

[E.W.]

if you take it in for warranty work, it could lead to some issues
You have a point about the warranty, no one seems to have an answer of how to improve the milage.

[wolowic1]

What kind of tire pressures are you running? If I were you I'd run them a little higher on the psi more towards the max---this can help some. I run mine 70 to 75 psi always and especially the fronts at 75 psi due to the weight. The backs can be a little less unless loaded or towing. I know some people run 50 to 55 psi which I think is too low especially on the fronts. More pressure is going to improve your rolling resistence on the tires which in turn should help mileage some. I've upsized one size as well to LT265/16/E. Sure you give up a little bit in ride comfort, but that doesn't bother me much with diesel prices where they are. $3.79 today here and fill-up was $92!! WTF!!! Summer blend fuel will be coming soon and that's going to help 1-2 mpg for most people living north. At the same time if recent history is any indictation gasoline prices will keep rising and diesel prices should start backing off to where they end up about the same by May.

[Philsauto]

The Shell station near my shop has gone up 10 cents a gallon each day, the last two days. $4.19 a gallon! OUCH! Other stations in the area are at $4. I really don't understand it.

On my 01 LB7 Crew Cab long bed, the Bully Dog programmer set at mid power level has improved my highway mileage significantly, but I don't find any difference around town. I drive only 3 miles to work, which is about the worse possible driving for fuel economy. I get only 13mpg with that kind of driving. But it does go over 20 (with the Bully Dog) on the highway, unless I am towing.

[wolowic1]

I seen $3.95 here today about 1 hour north of Chicago near the Wisconsin / Illinois line. I'm actually surprised you aren't higher considering some of the news about California prices. I have relatives in San Fran. and I know it's out of control there. I'm similar to you in that I only drive 6 miles each way to work and the truck never does get up to standard operating temp. unless it's summer weather----worse possible conditions for mileage for sure with short trips in city/highway combo type driving.

2001 LT 4X4 Crew Cab short bed---69K with original injectors and all runs good. Had a recent issue with NSBU switch going out taking the starter fuse/relay with it and they claimed to have found a flat spot on the starter which got changed out as well. Other than a few other minor issues all is well from day 1.

[Hook_'em_Horns!]

Yes, but I am not going to have it inspected, it is only required when you sell the vehicle in Maryland.

OMG...and I only thought burned out brake lights were rampant ;)

[Dakster]

H.W.;

In Florida, in nasty bumper to bumper traffic I get 11.5 - 13. The regen makes it hard to really tell. Right now I am having the regen too soon issues and my mileage will go down to under 10.:eek: On the highway in Florida I get 15-16. Closer to 15 for my trips to the keys, but I usually have 1k - 2k in the bed for one direction. I just broke 6k miles and I bought the truck new 10 months ago. I know, I know, I shouldn't overdrive it and I am trying to cut down on how many miles a year I drive.

I drove to Tennessee last summer and I was getting 18 on the highway and 15- 16 in the city... I dropped to 16 on the highway when I hit I-95 just south of Jackonville. I can't explain it and I gave up trying to understand it. Mileages were different, but this has been the pattern no matter what I have driven on long trips. (Mecury Gran-Marquis, Gas Excursion, Diesel Ford Excursion, Diesel Ford 6.0 F250, Chevrolet Van (gas), GMC Yukon XL Denali, Chevrolet Suburban 2500 Gas, and now Chevrolet Silverado (Diesel).

[wolowic1]

That Tennessee stuff at 18 and 15-16 mpg doesn't sound too bad considering you are running an extra set of tires on the pavement on that 3500. I'm learning more about that regen stuff and it sure doesn't sound good. Was planning maybe a new truck in another couple years, but I sure hope they've moved on to something better by then. I wonder if that super hot humid weather you get down there has something to do with the drop in mileage? I'm guessing it's just not breathing as well running in those conditions probably 90 plus degress and high humidity. Gassers are the same---my boat with an 8.1 (496) 425 hp is the same way---loves 70's and 80's, but 90 plus starts killing the performance as it seems to do with all types of internal combustion motors.


2001 LT 4X4 Crew Cab short bed

[Dakster]

I believe you have the same reasonings I do regarding mileage. However, I have a single rear wheel, not a dually.

I'm not complaining about mileage it is consistent with my previous, non-regen vehicles, except the 2wd excursion I had. It routinely got 16.5 in the city and 22+ on the highway. I attribute some loss to the 4wd system...

[Kennedy]

How would anyone no you didn't have it unless you told them? Is there anything else that would help the milage.


I've worked with several customers to eliminate the codes associated and combining this with my Kennedy Custom tuning generally yields best ever mpg (I make no promises, but it about always helps mpg) and much less hassle. Key here is to be able to return the truck to bone stock if necessary for a dealer visit.