Gas Milage On A '15 GMC 2500 HD

KCTractors

Member
Location
Central Wi
I went from a 05 Ford Super-duty with a diesel to a 2015 GMC 2500 HD with the 6.0 gas and 4:10's rear-end. They come only with the 4:10. I knew it would be hard on gas, but this thing lovers gas. Pulling a 5th wheel camper that's about 10,000 lbs loaded and 12' 9" high, I get anywhere from 5.7 to 6.5 miles per gallon. That just doesn't seem right. I drove quad axle dump truck with 72,000 lbs. and it would get 6.5 to 7.5 miles per gal.
When I pull a 14,00 lb flat bed trailer I get about 9.5 to 11.0 per gal. I would have liked to get the diesel, but Dealer said, I didn't use it enough for the additional cost. I had my Super-duty for ten years and had 34,000 miles on it.SIL wanted it so I let it go.
Anybody else have one of these and how is your mileage. I do like the truck.
 
I have a 2011 GMC 3500HD crew cab long box SRW, with the 6.0L gas. Yes, it is a thirsty beast. Empty, I see around 15 Imperial MPG. Pulling my 24' Precision gooseneck (heavy!) with a 12,000 lbs. tractor, I get around 8 Imperial MPG.

There are a few perks though. It will pull absolutely anything you put behind it. No joke. I've had a 14,500 lbs. trackhoe on said gooseneck behind this truck. No problem. Also, the 6.0L is an LS series small block. Meaning it doesn't mind revving high, and is a very, very tough engine.

I thought about buying a diesel, but I can put a lot of gas through this truck before I can justify a diesel.
 
If you are only driving the truck 3,400 miles a year, lower gas mileage won't cost you much money. Of those miles, how many miles are you towing a heavy/tall trailer, 500 or 1,000 miles per year?

You can always do the math to figure out how many years it would take before the diesel would break even with the gas engine.
 
That's probably accurate mileage. My 04 6.0 is in the same ball park for mileage.
In 3 years I put about 20,000 miles on a truck.
Of all that, maybe 3000-4000 miles are towing.
The thing will tow my gooseneck good. The cost of the diesel would not be worth it. I had a 12 valve cummins and it was great, but I didn't pay much for it. When it came time to get another truck, the 6.0 was the obvious choice for a truck that I only tow occasionally with. Its a heavy duty gas truck, so the mileage is not going to be good. But the cost of ownership is less than the diesel.
 
Truck's got a double-overdrive so the 4.10 isn't that bad.

Best you can expect out of these is about 15-16 MPG empty *HIGHWAY* and then only if you baby the throttle.

You bought the truck new and only drive 3500-ish miles a year, so it's still breaking in. I think the computer purposely runs the mixture rich through the first 5000 miles. Once you get about 5000 miles on it the mileage will improve some.
 
You could change the gears in front and rear axles...but it won't do
much good. In the early to mid 2000's GM did extensive testing on gas
2500Hd trucks with both 3.73 and 4.10 gear ratios. The result was
almost identical fuel mileage with mixed driving. However the 4.10
excel when pulling so that's what they went with.
 
I have the same truck KC. I knew going in that it does like to visit gas stations alot. I avg. about 7 - 7.5 mpg pulling a 30' flatbed gooseneck loaded or not. When i'm not hooked up to the trailer i get from 12 - 14 mpg. I do like that fact that i believe i could pull the world with the truck, if i can get traction!
 
(quoted from post at 09:58:03 06/07/16) I have the same truck KC. I knew going in that it does like to visit gas stations alot. I avg. about 7 - 7.5 mpg pulling a 30' flatbed gooseneck loaded or not. When i'm not hooked up to the trailer i get from 12 - 14 mpg. I do like that fact that i believe i could pull the world with the truck, if i can get traction!

I own a 2001 3500 with the 8.1 engine and 6 speed manual. MPG is about the same as you describe.
 
Haven't towed with mine yet but empty does a consistent 14.5 running 80 down the interstate and gets 17-18 running 60-65 normal hwy driving. So far very happy with the truck. The only thing I'm wondering about is my wife's Yukon XL with the 5.3 in it will literally smoke my 6.0 off the line but my 6.0 truck has alot more power at cruising speed. It's night and day different between the two.
 
The 6.0 truck is probably heavier. And the 6.0 throttle by wire has a slight delay when you mash it. Whereas the 5.3 probably isn't throttle by wire.
 
(quoted from post at 04:19:18 06/08/16) The 6.0 truck is probably heavier. And the 6.0 throttle by wire has a slight delay when you mash it. Whereas the 5.3 probably isn't throttle by wire.

We have a 2012 Silverado with the 5.3. It IS throttle by wire, and yes, there is a delay when you mash the pedal. My '01 with the 8.1 is also throttle by wire, and it has a delay also.
 
Both our Yukon and Sierra 2500HD are the
same throttle. Talked to a guy at work
today and he seems to think it's because
the trucks ECM is programmed different.
I can see that I guess but the
difference in how these two drive is
unreal. I hadn't driven the wife's Yukon
for over a month because I've been
driving my truck all the time and I got
in it this weekend and I was like holy
crap this thing runs. Make me wonder if
something isn't wrong with my truck???
 
I have a GMC 2009 2500hd with the 6.0 4wd and extended cab with long bed. Not sure of gear ratio. It was purchased new and now has 305,000 miles. Engine was replaced at 265,000. It dropped a valve on #2 cylinder and with the high mileage I decided to go with a reman and warranty. I travel extensively as the miles show with a lot of interstate driving. At 60-65 mph on interstate empty it will average 16-16.5 by being easy on the pedal. Mileage drops when using cruise control. At 75 the mileage will drop to about 14. I occasionally pull a 20+5 Pequa dovetail with dual 6000 lb. axles. Mileage when pulling this trailer is about half of empty mpg when pulling a 7000 lb. load at 60 mph. I did do a stretch from Knoxville Tn. to Tunica Miss. and ran betweem 70 and 75 pulling a 7000 lb. tractor. Mileage was less than 6 about 5.8. I like the truck and the 6.0 likes the rpms especially when towing. It will get the job done but uses fuel accordingly. Body is still very good and shines up like new. Transmission has not been touched other than scheduled maintenance. If I pulled the trailer more I would consider a diesel but my towing is less than 5% of my total miles.
Hope this helps.
 

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