Whats the avg you guys are seeng?

I average 17.5 through the summer but i am far from easy on it. About 15.5 in the winter on winter blend fuel.

Now your going to see some doing 13 to like 20 plus all stock. They can be the exact same setup and all be different.

Brian

I have not real summer numbers to give out as I bought mine in the middle of Oct. '08. So pretty much from the get go I have been running on at least some blend of winter fuel. My best highway mpg has been 18.2mpg (200 miles w/ cruise set at 71mph). City wise, it sucks, 12.3 is the norm, best has been in the mid to high 13's.

I get 15 almost every tank, but I have seen 16.5 from diesel at one certain station.

Well I know the 3500HD is not made for fuel mileage. But I get about 17mpg. I am easy on it. When I hard on it I get about 15+mpg. I see it this way, I bought it to work, not fuel mileage. So I think I get GREAT MPG!!!!

Had my 08' for a month now and I am getting 16 city and 19 hwy.

thanks guys, ive been tinkering with the idea of getting one, i found an 08 CC LTZ on a lot up here I think I can get for 36 TO 37 so its giving me that itch, if ya know what i mean. the only problem is that its red...not my fav but its a good deal.

Winter 14.5 Average
Summer 15.5 Average
Before Any Mods I Was Getting 17.5 Average In Winter.
Highway Only Unloaded Ive Seen As High As 18 With All The Mods

I would say that my average is between 15-16mpg. If I tow in town, I'll get down to about 13.5 and if I'm on the highway unloaded, I've seen 22-22.5mpg on a few trips. Usually 20mpg on the highway. My mods are listed below, but they haven't helped much with mpg (maybe 1-2mpg). The way you drive has the biggest effect.

15-16 in the winter....17-18 in the summer.........20-21 on highway trips during the summer

I've only got 1,000 miles so far. Lie-o-meter says I average between 14.3 and 15 mpg. Hand cals are a little more disappointing...more like 13.3 mpg.

Seems average compared to other diesels I own/have owned. My driving is mostly in town/rural highways with stop lights spaced about every 2 to 3 miles. My truck is 4 wheel drive. I have not towed anything yet. 2009 LMM crew cab short bed.

Nate

18-19 HWY. If i go easy, interstate driving, noload, and keep it arounbd 60-65 mph, i will get a little better, 21, give or take a little. City and around town, around 16. I will be driving 3,000 miles (1,500 round trip) in May and will keep detailed records to post when I get the chance.

16-17 overall avg. On the hwy as high as 20.

16.5 with alot of 2 lane highway at 60ish

So it seems like people are getting around 14mpg average city. Is this with the DPF on???


The 6.0's are seeing about 11mpg city...

I get......drum roll.........10-12

I get 12.5 around the town. My city driving consists of 10 miles which takes 30 minutes of stop and go. On the highway at 70-75 I get 17-18. I have a CCLB 4x4 which is stock.

I get 17 highway if i keep her around 65 mph.

Looks pretty consistent mileage over all. I posted earlier with average but run straight flat highway I am around 20 at 70mph with a tune from Nick. Nearly 21.5 at 55mph. I have modified it some and looks like I lost a bit. Added turbo breaking which is pretty cool around town in tow/hual mode which locks the torue converter in 2-6 gears when slowing. Only apply when over 900 rpm. Once 899 rpm or lower is reach drop turbo vains to 40 percent versus 95 percent when turbo breaking. Found this info for that on here for turbo breaking.

Brian

I start drooling when I see 20's.... It's been a while since I've driven anything that gets 20mpg...

Yeah that was what I thought myself but this was only 25 miles and once I got on the interstate I reset it. Dic has been pretty close based on manually figuring mileage by hand. I need to do a 3 hour non stop drive and see just how reliable this is. I hope not far off. And damn glad back to summer diesel. Winter diesel and warm-up in the mornings suck fuel bad. But on average I do 17 for 60/40 highway/city driving so far this summer. 15 in the winter. Normally not too easy on it. Love getting up to speed I want then just let it hold it at 70mph from there. Maybe if I speed up slowwer maybe slightly better mileage but that would be no fun and would be able to get the 5" turboback exhaust cleaned out. I hate soot build up inside the exhaust :D. But not on the rear bumper ):h.

Brian

Now... i was prowling the ford forums, and they blame their lack of fuel economy on the young engines. They say that after about 15k, you'll start seeing dramatic improvements in fuel economy.

Is there any truth to that, or are they just getting their hopes up?

Seems all diesels get better mileage as the miles rack up. That is the claims i see here on Duramax engines. They just need to be loosened up some.

Brian

22.5 driving like a granny down the 5 going 70.

Very nice mileage. What are your mods on it.

Brian

no mods, just dont drive like a moron. If/when i want a faster vehicle, i go get into my father in laws Corvette.

08 Duramax 13,500 Miles I Get 11.1 Mpg Never Seen Over 13.2 Since New Doesn't Matter If I Am Just Driving Or Pulling. My 06 Was Alot Better

I have my 2009 GMC 5 weeks so far, 3600 miles and getting in the city driving 16.5 consistently and the highest on highway was 18.8. This truck rides so much better than my 2004.5 LLY, it is a pleasure to drive. the mileage was confirmed also by hand calc. It seems my DIC is pretty accurate once I realized to clear all of the information. On the 04, i was able to clear one item and it cleared them all, this truck i have to clear the mileage, the fuel used, the average mileage used to be sure it is accurate.

I'm very confused by the range of numbers. Maybe if you guys can include your actual truck setup, that would help:


-Stock, Tuned, Exhaust, Intake?
-2500, 3500??
-4x4 or 4x2?
-Dually? SRW??
-Crew Cab? Extended Cab
-Bed Length? Bed Cover??
-Stock Tires?
-Aftermarket bumpers, lift, etc???
-Where you live: Hilly, flat... warm, cold climates???

Maybe the great range could be better explained by including the variables.

I, for one, would be getting a 4x4 z71, Extended Cab 2500, regular bed...

My truck is below - stock factory tires not listed 265/70 - r17
my mileage on the truck is aprox 10200 since july 1 08 and the avg mpg total is aprox 15.6 mpg for the life of the truck.
my driving is easy on the go pedal and aprox 60% city 40% highway and includes my first winter that just passed.

-Stock, Tuned, Exhaust, Intake? PPE tuner, 4" turbo back, s&b intake, egr blocked
-2500, 3500?? 2500
-4x4 or 4x2? 4x4
-Dually? SRW?? SRW
-Crew Cab? Extended Cab? CC
-Bed Length? Bed Cover?? 6.5' bed - coverede
-Stock Tires? 285/70/17
-Aftermarket bumpers, lift, etc??? leveling kit
-Where you live: Hilly, flat... warm, cold climates??? in So Cal, terrain varies. I live on the edge of foothills with a lot of city driving.
unloaded: city avg. 13.5, hwy avg. 19 - 19.5 (@ 75mph)
loaded (12,000 lbs): city avg. 6, hwy avg. 9 - 11 (@ 60 mph)

when unloaded, usually running tuner @ 160 hp or 225 hp tune
loaded, running 90 hp tow tune.

-Stock, Tuned, Exhaust, Intake? PPE tuner, 4" turbo back, s&b intake, egr blocked
-2500, 3500?? 2500
-4x4 or 4x2? 4x4
-Dually? SRW?? SRW
-Crew Cab? Extended Cab? CC
-Bed Length? Bed Cover?? 6.5' bed - coverede
-Stock Tires? 285/70/17
-Aftermarket bumpers, lift, etc??? leveling kit
-Where you live: Hilly, flat... warm, cold climates??? in So Cal, terrain varies. I live on the edge of foothills with a lot of city driving.
unloaded: city avg. 13.5, hwy avg. 19 - 19.5 (@ 75mph)
loaded (12,000 lbs): city avg. 6, hwy avg. 9 - 11 (@ 60 mph)

when unloaded, usually running tuner @ 160 hp or 225 hp tune
loaded, running 90 hp tow tune.

What more could we ask for. Good answer.

-Stock, Tuned, Exhaust, Intake? stock w/ hypertech stage 1 tune (testing mileage)
-2500, 3500?? 2500 w/ 25k miles
-4x4 or 4x2? 4x4
-Dually? SRW?? SRW
-Crew Cab? Extended Cab? CC
-Bed Length? Bed Cover?? short bed
-Stock Tires? 285/75/17
-Where you live: Hilly, flat... warm, cold climates??? north AL. mix of 4 lane, back country roads, fields, hills, and then the dreaded stop and go of the city
unloaded: city avg. 15.5 (if i take her real easy), hwy avg. 18-18.5. (seems to be a hair better if I don't use cruise control and thats if the DIC is right)

Only had this truck a few weeks. Still learning it out good.

Just took a 440 mile trip- mostly hiway at 62MPH = 21.5 MPG with Edge race on 3 no DPF and stepping on it a few times

I just filled up last night and either I had a regen, kangaroo fuel runs like a turd, or my truck is just extra thirsty. 70/30 hwy miles so far on this tank and DIC is showing 13.6... but at least its on the rise.

B

This is just incidental information to add to this thread. My '08 3500 Crew dually has 7,000 miles on it and is completely stock except for airbags and Torklift Super Hitch Magnum receiver hitch - No "effect-on-mileage" mods whatsoever.

I only drive it around town on night and weekends because I have a company car. In that mode, I get 12-13 mpg which sucks but its still better than my 2002 Dodge 1500 4x4 got. That had the small 4.7 V8 which was too little for that truck's weight so it got awful mileage.

Yesterday, I filled up my truck right before taking a 40 mile drive. Traffic was light on the freeway so I set the cruise at 60 mph just to see how it would do? I was relatively unloaded - maybe 200 lbs in back. The mileage per the computer just kept climbing and climbing, it got all the way up to 19.7 mpg (!!!) before I got off the freeway and of course it eventually dropped into the 15-16 mpg range by the time I got home. I THINK this is an indication that on a long trip I could get dramatically better mileage if I kept the rev's right at or near the optimum torque rpm of 1600. As I said, just incidental.

Later in the month I will be driving from SoCal to Lake Powell and back with my 4000 lb Lance 1181 on the truck and towing my two Jet Ski's for the first time. I will be caravaning with my brother in law's Class A motorhome so I will probably keep the speed down. It will be interesting to see what mileage I get with all that crap on it, but at 65ish the whole way?

Just picked one up yeserday,said 11 when i start and was up to 18 by the time the 2 hour drive was over

I have my mods listed below. I average 17.8 combined with my EconoMind on level 6. I make 160 mile runs up to north western OK a few times a month. I can get as good as 22.3 or as bad as 16.8 on that trip. The wind and my foot make all the difference. The 22.3 trip was three weeks ago at 71 MPH average with a tail wind. I use the DIC for fuel economy. I calculated by hand and compared and it was 2-6% difference. I did calculate my towing economy both ways on a trip to Texas the other day. Once again, 4% difference between DIC and hand. Towing my 6500# brick into and through a storm for 320 miles I averaged 11.8. I was pissed. The weather cleared and on the return trip I got 14.6. I also note that I can average over 20 and then hit I-44 and run 85 to keep up with the flow of traffic and watch my mileage drop like a rock. Breaking that 2000 RPM mark is murder. Just like my previous Duramax, an LLY comparably modified, speed is the key. I'm hoping my LMM breaks-in like my LLY did and I see a 2-3 MPG increase after 15-18K.

City avg 15.5 winter 17.5 summer 34000 miles