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Bartman432 06-23-2017 07:28 PM

What kind of hwy mileage are people getting?
 
Last week, I got my best to date, and part of it was in some heavy traffic. I got 627 miles with an average of 18.5 from what the computer said. Most of my freeway miles I had the cruise control set at 75. I did put in slightly over 35 gallons when I filled up:eek: My truck has about 4500 miles on it now. I love this thing.

birtch3 06-23-2017 07:46 PM

I'm always running the cluster in Metric because Canada... but best I have seen was on the highway and my average went down to 10.8L/100km (21.77MPG), but fairly consistently in the low to mid 11L/100km (highway). In town and such I have yet see a tank average over 12.7L/100km (18.5MPG)

dz302 06-24-2017 05:13 AM

I'm averaging 19.5 miles per gallon on my 2017 CC.....just under 5k miles on the truck...
Awesome trucks !

Ramler 06-24-2017 01:51 PM

Just got back from a 2500 mile trip to Kentucky in my 2500 HC. With a slight tail wind for the first 300 miles I got 23mpg, then at the 900 mile point, regen took me down to 22.1. On the way home I was getting 22.5 until I hit a regen and a 30mph head wind. Ended up the last 1300 miles at 20.4. Overall was very close to 21.5. Most of the miles were at 70mph. With 6000 miles my On Star phone app shows17.6 lifetime average. About 400 miles of that was towing my 35 ft. travel trailer. I'm satisfied.

ssm58 06-24-2017 08:37 PM

I have had mine about 6 weeks and have 12,100 miles on it and about what Ramler gets for mileage. Got a little better with my 2007 but with mods and no emissions. Just sold that one with 650000 miles.

timoloco 06-26-2017 08:47 AM

Im getting about 21-22 mpg on my 3500 SRW and I have just under 2000 miles on it. I get easily 600 miles to a tank.

johnjr 06-26-2017 08:06 PM

You guys need to get something hooked up to those trucks. I have 3000 on mine and the dic says 11 mpg. 1200 miles towing, the rest highway 70-75 mph.

birtch3 06-28-2017 10:53 AM

Quote:

Originally Posted by johnjr (Post 9169106)
You guys need to get something hooked up to those trucks. I have 3000 on mine and the dic says 11 mpg. 1200 miles towing, the rest highway 70-75 mph.

Only towing I've done so far was a 19' v-nose sled trailer and a 27' car hauler. 17' was a short trip to sell to the new owner, and my 27' was just a 250km trip home. :confuzeld

I hadn't seen this thread until after both of those things so fuel mileage wasn't the most important thought on my mind.

Also, I've only got about 6,500km on the ODO currently... wanted to get some decent mileage on the truck before I really started using it. I can definitely give towing mileage feedback in the near future.

BanksLB7Duramax 06-28-2017 10:58 AM

Quote:

Originally Posted by birtch3 (Post 9171842)
Only towing I've done so far was a 19' v-nose sled trailer and a 27' car hauler. 17' was a short trip to sell to the new owner, and my 27' was just a 250km trip home. :confuzeld

I hadn't seen this thread until after both of those things so fuel mileage wasn't the most important thought on my mind.

Also, I've only got about 6,500km on the ODO currently... wanted to get some decent mileage on the truck before I really started using it. I can definitely give towing mileage feedback in the near future.

You don't need to worry about getting mileage on the truck before you start using it. They're designed to be used for towing pretty much immediately. The biggest concern is wearing in the ring and pinion which already happened thousands of miles ago on your truck.

D.Camilleri 06-29-2017 11:58 PM

Picked up my new 5er in Longmont CO two weeks ago. Trip home, Denver to Casper, WY, 7.1 mpg bucking a 20+ mph head wind. Casper to Worland, 11.1 no head wind. Cruise set to 68, pulls like a beast. 5er is a 2018 Solitude 310GK, combined weight of 23,300 lbs. Next trip I will load her down!

Mileage running empty seems to be averaging around 18.5. Mileage will jump to around 22 and then regen sucks the mileage out.

Nosmokelml 07-09-2017 09:20 PM

2 Attachment(s)
Cruise at 71. 4x4 cc Denali

Ramler 03-14-2018 10:34 AM

Just turned over 15,000. Phone app says 18.5 lifetime. Normally 20-22 on long trips running empty. 11-13 towing my 7,000 lb. trailer.

Jeepmanmatt 03-15-2018 12:26 PM

Highway mpg between 18-20 unloaded depending on the terrain and speed.

joechet 03-31-2018 08:11 AM

5,900 miles on truck, Lifetime avg is 15.5. Just returned home from a 3,400 mile trip from cooler temps to the Gulf in MS. 90% interstate driving, trailering a Uhaul auto transport with a car on it and very little weight in truck, cruise set at 73 most of the time. Avg 14.9 mpg / Avg 1 gal DEF each 680 miles, 75psi all tires, (unloaded daily driver use 65 fr / 50 rear). Better fuel mileage in the warmer weather. Truck has plenty of power and rides smooth. Very satisfied so far!

BeastGMC 08-14-2018 12:42 PM

I drove mine from Dallas Texas to Raleigh NC through the mountains and ended the trip 18.8 MPG. Way better than the tahoe I sold to buy this truck!!

1thackattack 08-22-2018 02:08 PM

I was averaging 24.7 at 75 on I-15 the other day


Sent from my iPhone using Tapatalk Pro

BanksLB7Duramax 08-22-2018 04:29 PM

Quote:

Originally Posted by 1thackattack (Post 9737842)
I was averaging 24.7 at 75 on I-15 the other day

For how many seconds?

1thackattack 08-22-2018 04:35 PM

Quote:

Originally Posted by BanksLB7Duramax (Post 9737882)
For how many seconds?



Lol, not seconds, it lasted for quite a while once i had been driving on the freeway for a little

oldschoolbowtie 08-22-2018 06:26 PM

Quote:

Originally Posted by 1thackattack (Post 9737890)
Lol, not seconds, it lasted for quite a while once i had been driving on the freeway for a little

:thumb: impressive

CntrlCalDmax 08-22-2018 07:02 PM

Quote:

Originally Posted by 1thackattack (Post 9737842)
I was averaging 24.7 at 75 on I-15 the other day


Sounds just like my Dodge friends!

JBear 08-22-2018 07:27 PM

I've never broke 23 with my Dodge... just sayin' LOL

clarythedrill 08-22-2018 07:43 PM

Within the last month I have taken two long distance trips. First from Chicago to Charleston, SC and back. Second from Chicago to Killeen Texas and back. Both trips with the A/C on and going about 3-5 mph over the posted speed limit, so averaged about 75 on all trips. On both my hand calculated MPG was anywhere from 21 to 23, depending on the hills, or lack thereof. I am extremely happy with the overall performance of my '17 model, which is currently sitting at just under 18,000 miles.

maxinDixon 08-22-2018 10:55 PM

Quote:

Originally Posted by 1thackattack (Post 9737890)
Lol, not seconds, it lasted for quite a while once i had been driving on the freeway for a little

Downhill of course with a tail wind lol. Last trip from CDA to granby CO 20.0. CDA to Santa Clara, CA and back 20.0 and that with an LML going 80 much of the time,

steakman 09-06-2018 11:53 AM

yea some pretty impressive claims to be sure.

Add in your Regen and then re-do this thread. Add cost of DPF fluid.
Then lets see where you guys are at.?

for the record - Truck wiht me in it, Tool box - Full Titan & slip tanks - ~8000lbs
Hiway at 75 . 20 - 21 avg.
Towing 12k 5r . 10.0 avg. (BC Mountains)

EFI Live on 3 (45hp)
265/70R-17 BFG Rugged Trails
No Lift - levelled

Calculated

oldschoolbowtie 09-06-2018 07:32 PM

Quote:

Originally Posted by clarythedrill (Post 9737988)
Within the last month I have taken two long distance trips. First from Chicago to Charleston, SC and back. Second from Chicago to Killeen Texas and back. Both trips with the A/C on and going about 3-5 mph over the posted speed limit, so averaged about 75 on all trips. On both my hand calculated MPG was anywhere from 21 to 23, depending on the hills, or lack thereof. I am extremely happy with the overall performance of my '17 model, which is currently sitting at just under 18,000 miles.

:thumb::thumb: those are awesome numbers

clarythedrill 09-07-2018 06:54 PM

Quote:

Originally Posted by steakman (Post 9743488)
yea some pretty impressive claims to be sure.

Add in your Regen and then re-do this thread. Add cost of DPF fluid.
Then lets see where you guys are at.?

for the record - Truck wiht me in it, Tool box - Full Titan & slip tanks - ~8000lbs
Hiway at 75 . 20 - 21 avg.
Towing 12k 5r . 10.0 avg. (BC Mountains)

EFI Live on 3 (45hp)
265/70R-17 BFG Rugged Trails
No Lift - levelled

Calculated


What do you mean by "add in your Regen and then re-do"? The amount of fuel used during regen is already in the calculation.

Meathead 09-11-2018 11:28 AM

I love all the insanely high mileage numbers. Somebody averaging 20+ mpg in a 8,000+ lb truck kinda cracks me up, 'cause it's obvious the truck isn't working. I'm all about freedom - if you can afford it, and that's what you want to drive and want to do with it, have at it.

I'm also all about OCD..

My '17:

80,922 miles

5,048 pulling an 8.5'x16' enclosed trailer, averaging approx. 5,000 lbs

19,142 pulling a 28' GN, loads all over the map, from approx. 6,000 empty, to roughly 20,000 lbs of trailer, skid steer loader, and attachments - roughly half of those miles loaded, and half empty

3,187 pulling a 36' fifth wheel


6,193 gallons of fuel
125 gallons of DEF


I've seen the 50-mile average numbers in the neighborhood of 20 mpg when running empty, but when you do other things with it, that number is meaningless. The concern over mpg is primarily a financial matter - cost of fuel per mile, per year, etc. This works out to a very tiny hair over 13 mpg for it's now 20-months-and-five-days career. Given what I've accomplished with it, I'm more than happy with that.

ata9977 09-24-2018 11:29 AM

I am just over 1,300 miles on my 2018 and in mixed city/hwy driving am seeing 13._ MPG.

the Same type of driving in the LMM I sold was right around 15.5MPG

moosetags 09-27-2018 05:59 PM

We recently completed a 73 day, 11,500 mile trip from Florida to the Pacific Northwest and back. 7,600 miles were done pulling an 8,000# Airstream travel trailer. Our average mileage for the whole trip was 13.26 mpg and the average price per gallon of Diesel was $3.24.

Brian

Coolbreeze 10-05-2018 09:04 PM

Overall life time average is right at 16.2 with about 15% of the mileage towing.
Maybe 30 % highway and the rest local.

As for highway mileage I would say I'm at about 19mpg. I some times see 24 on the lie-0-meter and right then a regen will kick in and it will go to 22 yet when I actually buy fuel and hand calculate it I see like 19mpg to 20 mpg. I have yet to ever have one full tank run highway all the way.

MRBASS 10-05-2018 10:43 PM

Wow, some pretty wild mpg numbers in this thread!
My 2017 3500 srw L5p gets an honest 16.5-17 not towing, and all my roads where I live are 55-60mph. I do a fair amount of idling while riding property lines and etc.. interstate highway, my cruise is usually set close to 80, and I get 17-17.5.
Towing my 5ver, and boat, gross about 26000, 75mph on the highway, gets me right around 11.
Pulling the race car trailer, weighing about 12000, plus the truck, it hangs around 11.5, running 75-80.
I also have 275 cooper stt pro mud tires, front and rear road armour bumpers, which I’m sure makes the mileage worse. The retrax bed cover didn’t change mileage either.

It’s a truck, that’s meant to work. And this mofo toes like nobody’s business! I actually wouldn’t care if it got 10mpg, yes, it tows that good!!!

SonnyAK 10-05-2018 11:18 PM

Quote:

Originally Posted by MRBASS (Post 9753958)
Wow, some pretty wild mpg numbers in this thread!
My 2017 3500 srw L5p gets an honest 16.5-17 not towing, and all my roads where I live are 55-60mph. I do a fair amount of idling while riding property lines and etc.. interstate highway, my cruise is usually set close to 80, and I get 17-17.5.
Towing my 5ver, and boat, gross about 26000, 75mph on the highway, gets me right around 11.
Pulling the race car trailer, weighing about 12000, plus the truck, it hangs around 11.5, running 75-80.
I also have 275 cooper stt pro mud tires, front and rear road armour bumpers, which Iím sure makes the mileage worse. The retrax bed cover didnít change mileage either.

Itís a truck, thatís meant to work. And this mofo toes like nobodyís business! I actually wouldnít care if it got 10mpg, yes, it tows that good!!!

That's almost exactly what I'm getting with my '18 Denali 3500 under similar circumstances. Zero complaints...It certainly is a towing beast!!

wensteph 12-01-2018 08:18 AM

2019 2500 with 1,000 miles. I had a 50 mile average of 20.3 at 75 mph. Light traffic on I 16 from Macon to Savannah which is slightly downhill (400' to sea level). 76 or 77 mph dropped me into the high 19s.

redwngr 12-01-2018 12:13 PM

first 9500 miles averaged 17.6 us mpg, hand calculated. (yes, I've been logging every fill)

I frequently do a 55 -60 mph run on rural 2 lane and if not windy it will run the 'recent average' up to mid 20's.
I usually don't refill til about 600 miles/1000km or so, and have never had a full tank average over 20 mpg.

Most daily driving. A little light towing.

Speed makes a huge difference, as does driving with lots of stops and starts.
Very little grad or elevation changes in this area.

It always runs a little less at 70 -75 than at 55 - 60.

Headwind or quartering wind also makes a difference - just like speed.

When running steady speed, the average will drop 10 mpg during a regen -- and of course recover when regen is done. Typically about 20 minutes/20 miles.

Regens usually about 400 mile interval, but occassionally less if more than usual idling or city driving.


Currently just under 12,000 miles.
Added def about 6500 and calculated about 1100 miles per gallon.
It's not asking for more yet. Like my LML, operational cost of DEF is insignificant. ($4/gal / 1100 miles/gal = $0.0036 per mile)

2500hd 12-02-2018 08:29 AM

2019 3500HD DRW, 24 miles on truck (yep it's brand new).

Departed from dealer in Houston TX and drove to Huntsville AL, Avg MPG was 17.4

ata9977 12-03-2018 09:33 AM

Omaha to Breckenridge, Co and back was about 1,300 miles and averaged 17.3 mpg running 80ish on the Interstate.

2017DenaliHD 12-03-2018 10:48 PM

Mixed driving up and down California no load I averaged 23 over 1200 miles.

moseso 12-04-2018 08:29 AM

Just got back a few weeks ago after a 5,000 mile trip from Burlington Ontario Canada towing 44 ft 5R, 16,000 lbs, going to Columbus OH, Nashville, Memphis, Baton Rouge, Biluxi, Gulf Coast Alabama, Perry FL and finally Orlando. Started with approx. 5,000 miles on my 2018 3500 HD Duri single real wheels. Mileage was all over the place with strong head winds, as low as 9.1 and as high as 11.5. Averaged 10.1 towing. Last year towed Orlando to Burlington and got 9.1 with the same trailer, so I think it is an improvement. My 2011 2500 HD got around 11 mpg towing similar size 5R. The 2018 is a towing machine, put it on cruise and let it go.

moseso 12-04-2018 08:30 AM

Sorry, forgot to mention trip home from Orlando got 21 mpg, no towing. Average speed 70 mph

2500hd 12-07-2018 06:49 PM

2019 3500HD Dually with 24 miles on the clock, drove from Houston TX to Huntsville AL and got 17.5 Avg MPG.

RDP 12-11-2018 12:34 AM

2018 GMC 3500HD with 100 miles, mostly short 2-20 miles trips till spring comes.
15 MPG

ata9977 12-11-2018 09:21 AM

Quote:

Originally Posted by RDP (Post 9775966)
2018 GMC 3500HD with 100 miles, mostly short 2-20 miles trips till spring comes.
15 MPG

I am in that same boat...

averey0 12-14-2018 08:16 AM

I've gotten as high as 20 or 21 all hwy on fairly flat ground. 19 with mostly hwy but a little stop and go and or slight hills. Now though with winter fuel i'm down to 17-18 in these same conditions. The current tank i'm on currently sits at 15.8 with mostly around town driving and maybe 20% hwy.

deminimis 12-18-2018 06:24 PM

Hey Kids. Some good numbers here. I recently sold my Ram 5500 and I'm thinking it's time to return to the flock (once I sell my new Tacoma TRD Pro). Time to just have one vehicle for me. Please keep those 3500 dually numbers coming!

wkayl 12-20-2018 10:04 AM

1 Attachment(s)
My road trip last August from Loveland. Co to Marshall, Mn and back.

jbogart812003 01-03-2019 10:07 PM

Got 17.5 mpg on the way home from the dealer but havent hit more then 15 mpg since. About 11.5 after the lift . Wonder if these new tunes will increase mpg enough to justify spending $4500 or are the just for hp/tq gains

Icutmetl 01-04-2019 08:28 PM

Roughly 1500mi on truck; cruise control set at 80-85 on long stretches of an 1100mi trip, I saw 15.5-15.7mpg.

redwngr 01-04-2019 10:23 PM

Sometimes speed is more important then fuel economy :rolleyes: :thumb:

wq93 01-05-2019 09:14 AM

Agree redwngr, another form of, "you gotta pay if you want to play" :)

With the poor aerodynamic form of big pickups, increased speed kills fuel economy due to air drag so unless you always plan your travels to run with a big tail wind it will cost you. Every time you double your speed on a flat road it takes approximately 8X more horsepower. Normally doubling the rate at which work is done would require only twice the horsepower but because the air resistance follows approximately a square law response you end up with 4 times the air resistance at twice the speed coupled with the need to increase horsepower to do the same work at a faster rate you end up wit the basic 8X equation.

Or put simply, it if takes 10 horsepower to travel 40 MPH your horsepower demand goes up to around 80 horsepower at 80 MPH and you will burn more fuel to generate this power.

So why don't you get 8X the fuel economy at half the speed? The 8X approximation is a pretty close rule of thumb at high speed but at lower speeds you are also overcoming additional drivetrain losses, rolling resistance, any road grade, etc. as you increase speed and the powertrain is designed and geared to produce best efficiency under typical operating conditions. So even at lower speed you aren't going to be challenging a prius in the fuel economy race but at 52-55 MPH you should get in the low 20 MPG range which might be important if you are very low on fuel many miles from the nearest station. On the other hand if you remove the speed governor from the programming and get the truck into the 110 MPH range then you probably will be in the 3-4 MPG range or about what you would get running the truck fully loaded up the Ike with the engine RPM at peak HP.

cowdoc 02-13-2019 05:58 PM

1 Attachment(s)
So far.........

deminimis 02-18-2019 12:34 AM

3500 SRW. 18.3 on the way home from the dealer.

ataboy 03-07-2019 09:25 AM

I sure hope my 19 gets better with time. I have 600 miles on it and it doesn't even come close to the 15 I traded in! The 15 would show around 20mpg on cruise at 65mph and the 19 is running around 17mpg on the same road.

redwngr 03-07-2019 04:56 PM

Quote:

Originally Posted by ataboy (Post 9804298)
I sure hope my 19 gets better with time. I have 600 miles on it and it doesn't even come close to the 15 I traded in! The 15 would show around 20mpg on cruise at 65mph and the 19 is running around 17mpg on the same road.

Tough to compare a well broken in one against one that is new and running winter fuel.

Mine will runs well over 20 at 65 mph on cruise, flat and no wind.

They do regen more often than LML, but the regen's are shorter.


I'd expect your 65 mph on cruise mpg to improve significantly.

ataboy 03-08-2019 08:25 AM

I hope you are right. I have had a 06, 11, 13, 15, and now this 19 and I don't seem to remember a big break in period but I could be wrong.

Yea I was surprised when in went into regen at 525 miles the first time and how fast it was done!

cowdoc 03-25-2019 01:05 PM

I just got 21.9 mpg (hand calculated) on a trip from North Alabama to the Smokey Mountains. My best, so far.

ataboy 03-25-2019 01:25 PM

Quote:

Originally Posted by cowdoc (Post 9808700)
I just got 21.9 mpg (hand calculated) on a trip from North Alabama to the Smokey Mountains. My best, so far.


How many miles on the truck?

Mine sure is not getting better and I drive like old man right now.

cowdoc 03-25-2019 03:31 PM

About 46k. Mileage improved about 1 - 1.5 mpg after I put the banks Derringer and CAI on it.

gmc502 03-25-2019 07:16 PM

Quote:

Originally Posted by cowdoc (Post 9808700)
I just got 21.9 mpg (hand calculated) on a trip from North Alabama to the Smokey Mountains. My best, so far.

how fast were you going?

cowdoc 03-26-2019 12:36 PM

Quote:

Originally Posted by gmc502 (Post 9808804)
how fast were you going?

Averaged about 75 mph. I usually drive 5 mph over posted limits.

Greg S 03-29-2019 12:53 PM

8.5 hauling a 40' trailer with 2 cars and loads of heavy tools in it. Averaging about 65-70 MPH. Really seemed to suck up the DEF with the big load on it.


Greg

redwngr 03-30-2019 11:22 AM

Quote:

Originally Posted by Greg S (Post 9810142)
8.5 hauling a 40' trailer with 2 cars and loads of heavy tools in it. Averaging about 65-70 MPH. Really seemed to suck up the DEF with the big load on it.


Greg

DEF usage is a ratio to fuel usage.

Use more fuel, it will use more def

Should be somewhere close to 1.5 gallons on DEF per 100 gallons of fuel.

DP218 03-31-2019 05:20 PM

This is what my 2018 CCLB has been doing. I have almost 18,000 miles on it since last July and overall hand calculated average is 16.53 mpg over the first 12,500 miles. The trucks on screen mpg shows around the same mpg as well with the best 50 miles at 25.1 mpg and best 400 at 20.7 mpg not towing either time. I run mine around 50 miles one way to work each day going around 65 mph and towing on weekends.

Greg S 04-01-2019 11:08 AM

Quote:

Originally Posted by redwngr (Post 9810374)
DEF usage is a ratio to fuel usage.

Use more fuel, it will use more def

Should be somewhere close to 1.5 gallons on DEF per 100 gallons of fuel.


Don't mean to doubt this but are you sure that is how its metered? I put in one of those blue DEF boxes and it seemed to be gone in two tankfuls at my towing consumption (8.5 MPG)

Greg

ataboy 04-09-2019 09:41 AM

Pulled the boat 400 miles round trip 65mph to 75mph and got 11.7. This is with a 18ft. boat. Scares me about thinking what I will get with the 35ft 5th wheel. I now have 2500 miles on the truck. Just doesn't seem right after pulling with my 2015!

Mikey52 04-09-2019 12:00 PM

Def consumption is a % of fuel used. If you use 100 gallons of fuel, you will use 1-1.5 gallons of def. So when towing, with lower miles per gallon, will yield more def use per mile.

BanksLB7Duramax 04-09-2019 03:33 PM

Quote:

Originally Posted by Mikey52 (Post 9812504)
Def consumption is a % of fuel used. If you use 100 gallons of fuel, you will use 1-1.5 gallons of def. So when towing, with lower miles per gallon, will yield more def use per mile.

From what I hear the L5P uses more DEF than that. They use quite a bit more than the LML.

redwngr 04-10-2019 11:16 AM

Quote:

Originally Posted by BanksLB7Duramax (Post 9812584)
From what I hear the L5P uses more DEF than that. They use quite a bit more than the LML.

My truck would indicated the 'quite a bit more' is a rumor started by those not correctly measuring consumption. (and those just wanting to hate on DEF)

Probably in part to the continuation of dealers not filling at delivery, complicated by adding to the tank, but not completely filling (so no way to know if it was filled to the same point as last time def was added).

Like the LML, the level 'indicator' isn't accurate enough for determining DEF mileage.



No doubt there will be some that have something wrong with them and will use an unusual amount -- just like happened with some of the LML's.


I guess this is a pointless discussion, unless we are provided with some sort of definition of 'quite a bit more'.

RDP 04-11-2019 10:46 PM

350 Miles @ 70 to 75 mph pulling my RV trailer into a 40 mph head wind with rain and snow.
9.4 miles per gallon. (2018 GMC 3500HD)

cowdoc 04-12-2019 05:00 PM

Average DEF usage is around 900 miles/gallon
Average distance between regens is around 830 miles
Average hwy fuel economy is 19.5-20 mpg
Lifetime fuel economy is 18.4 (about 80% hwy and/or rural roads; towing probably <10% of the time)
Best fuel economy (whole tank) is 20.4 mpg
All fuel economy numbers are hand calculated
49k on the odo

dslipp 04-19-2019 11:18 AM

25mpg going 55 on flat around with no wind.

moseso 05-22-2019 11:01 AM

Just got back from our semi-annual trip to Florida. 2018 GMC 3500 Duramax SRW with 16,000 miles on it. Left for Orlando from Burlington, Ontario Canada. Drove 1305 miles without towing; averaged 70 mph; got 20.8 mpg.
Towed 16,000 lb 44ft 5th wheel back home, total towing 1,250 miles (stopped in Niagara Falls Ontario); got 10.5 mpg towing.
I am really pleased with the 2018. The additional horse power and torque was really noticeable compared to my 2011 2500 HD Duramax. It did not gear down on most uphill climbs as the 2011 did. The best mileage I got on the 2011 was 11.1 mpg towing 14,000 40 ft 5th wheel, low was 9.9 mpg with headwind.

cowdoc 05-24-2019 11:02 PM

New best of 20.5

duramaxed12 06-30-2019 03:20 PM

Wow you guys are getting awesome mileage.

cowdoc 07-31-2019 08:44 PM

Update:
Best of 21.5 so far. Averaged 20.06 for June and 20.68 for July. Not too bad!

plumber19832003 08-01-2019 09:57 AM

mileage
 
with 4400 mi , with my driving habits i am getting 17-18 mpg. around 450-500 miles per tank.

cowdoc 08-01-2019 05:01 PM

Almost 65k on the truck and a lifetime average of 18.8 mpg. I have gone over 700 miles on a tank a couple of times. I get around 14 mpg pulling my 3-horse slant aluminum horse trailer with small living quarters.

Wagontrail 08-02-2019 06:19 AM

Did a 3000 loop, illinois to co, wy,into sd. Big grades, got 11.7, that was calculated by hand, waiting for the 21's . There is noise within gm of big things on horizon. Good friend of mine is in the upper eschalon at gmc, I'll let all know what uncle chuck can find out,,, see ya WT

wensteph 08-04-2019 05:05 PM

Savannah to Balsam, NC. 700 miles RT. Lots of IH95 and IH26 at 80 and stretches at 90 (when IH95 is running fast, it runs fast). Mountains (hills) on IH26 South of Asheville. Overall DIC was 18.3. For an aerodynamic brick at those speeds, I think that's pretty impressive.

lobster poutine 09-02-2019 01:00 PM

Quote:

Originally Posted by moseso (Post 9821634)
Just got back from our semi-annual trip to Florida. 2018 GMC 3500 Duramax SRW with 16,000 miles on it. Left for Orlando from Burlington, Ontario Canada. Drove 1305 miles without towing; averaged 70 mph; got 20.8 mpg.
Towed 16,000 lb 44ft 5th wheel back home, total towing 1,250 miles (stopped in Niagara Falls Ontario); got 10.5 mpg towing.
I am really pleased with the 2018. The additional horse power and torque was really noticeable compared to my 2011 2500 HD Duramax. It did not gear down on most uphill climbs as the 2011 did. The best mileage I got on the 2011 was 11.1 mpg towing 14,000 40 ft 5th wheel, low was 9.9 mpg with headwind.

just did the near identical trip - niagara on the lake to fort wilderness campground with a stop in knoxville. so a bit of the smokies.

got 11.5 MPG in the mountains - never checked the overall mileage on the trip meter yet.

D.Camilleri 09-02-2019 11:19 PM

Just finished towing 2200 miles to North East Saskatchewan and back towing an 18 ft fishing boat and averaged right at 15 mpg. Deringer in level 6 the whole way, 3 regens and 2.5 gallons of Def fluid.

averey0 09-04-2019 08:53 PM

Have 19000 miles on mine now and average around 20.5-21 on flat hwy at 65 or 70mph.


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Wnc-Silverado 09-05-2019 09:06 AM

Quote:

Originally Posted by wensteph (Post 9838544)
Savannah to Balsam, NC. 700 miles RT. Lots of IH95 and IH26 at 80 and stretches at 90 (when IH95 is running fast, it runs fast). Mountains (hills) on IH26 South of Asheville. Overall DIC was 18.3. For an aerodynamic brick at those speeds, I think that's pretty impressive.

You were up in my neck of the woods. I am from balsam.

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averey0 09-05-2019 01:17 PM

I will add that going to Ohio and Kentucky from the Carolinas I get about 19.5-20.5. Really depends on when a regen hits. This truck has been way more consistent than my 08 F250. Before I deleted the Ford I got 15-16 then after would get 17-20 depending on how I drove it on the hwy speed wise. This truck doesnít seem to care though much. The worst Iíve got is low 19ís and best is 21.5 or so. This is of course not towing and running 60-80mph depending on speed limit and traffic etc. Very curious what it could do when fully deleted.


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A Bad Habit 09-13-2019 12:50 PM

I thought I read in the supplemental duramx book, after the first 500 miles break in, you can tow whatever your rated for? I have been using mine as needed since then.


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