Mpg for new gas 2500

magnum74 · June 2, 2017

Wow the fuel economy on the 6.2 is really that low? I am shocked. My duramax does way better. And diesel right now is running almost 20 cents a gallon cheaper than regular. just got back from the coast going over I got 11 pulling my 5th wheel. On the way back (without the trailer) I was getting 23 mph. And those calculations include two mountain passes that I have to go over to get to the coast and some stop and go stuff at either end. That baby get better milage the harder I run it. It really likes to run at 1900 RPM which is at 65-70 mph.

It takes a lot of miles and fuel to reach a break even cost between the two engines and that's not including added maintenance costs with the Duramax. It's also not fair to include potential shop time requirements over the vehicles life because we can't accurately predict it but I know which one I'd put my money on to be trouble free. I don't think you'll find many of us hating the Duramax (myself, love diesel power) we just don't think the initial cost and O&M is worth it. A GM 6.0 is as close to maintenance free as it gets and will run all day on poor quality 87 fuel if it needs to. I can leave mine running in -40 temps for 24 hours without a care, same in hot weather. All it needs is to be fed clean air and a high quality synthetic when the meter tells me to. They both get 0 MPG when they're idling despite the cost and complexity but only one of them will do it trouble free for its lifetime.

mrailing · July 10, 2017

So many people complain about the gas vs. diesel and lower MPG. I'm currently at 15,000 miles with my 2016 (having it for 8 months). Average (hand calculated) life is 11.7 MPG, with towing, city, empty driving, and the dash shows me at 11.3 MPG. I drive downtown Louisville daily, 6 miles to work, and 6 miles home. I was taking surface streets but have switched to the interstate, and am getting 1 MPG better average on my commute. I have adjusted tire pressure as well, run 50 in the front and 60 in the rear, and have gotten 1 MPG better, increasing when I tow. This is playing with pressure and speeds, and a LOT of my driving hasn't been very conservative, so my overall average should increase.

I have now towed my toy hauler (7500 pounds fully loaded) 3 times, a total of maybe 2000 miles out of the 15,000 I have driven (average fuel consumption has been 7-8 MPG). I have hauled roughly 1,100 pounds (two motorcycles, two bicycles, restraints) 2500 miles. So roughly 10,000 miles of my driving has been unloaded travel. I typically average 20,000 miles a year driving. I typically drive the speed limit to 5 MPH over unloaded, and when towing, usually 65 MPH max, which gives me 1-2 MPG better than 70-75 MPH.

Later this summer I will be towing the toy hauler from here to Montana and back, so that will be roughly 4,000 miles of driving when done. I'll be curious of my consumption, and I plan to run 65 MPH most of the time to save a bit of fuel.

I wanted the diesel, but it just didn't pay off to get it. Diesel here is still more expensive than gas. I tried to do a lot of math to determine my cost and which might be better, and it did not pay off to buy the diesel. Here is what I used to compare my math. Being that I do mostly unloaded driving, I feel I have to look at that first (although it really doesn't matter, seems the spread for loaded/unloaded is 4 MPG across the board)

Diesel 14 MPG city/18 MPG highway (this is what I searched, and I realize some people get better, but this is what I was seeing as average, and I will give it the benefit of the doubt and give it an average of 16 MPG over city/highway)

Gas 10 MPG city/14 MPG highway (this was what was reported, and since owning the gas, what I experience as the average, so I will say 12 MPG average, since I was close to that above)

4 MPG spread

DEF Fluid is 1.25 gallons/100 gallons of diesel. Def Fluid is $6/gallon, so $7.50/100 gallons of diesel.

For simple math and figuring out the difference, we will use these average nationwide prices, and 100 gallons to figure out the cost difference.

$2.25/gallon for gas

$2.50/gallon of diesel

Gas = $225 for 1200 miles = $0.19/mile

Diesel 4MPG spread (plus DEF) = $257.50 for 1600 miles = $0.16/mile

$.03/mile = $3000/100,000 miles

This is again, quick easy math, and rough figuring, and ONLY looking at fuel cost difference. Average cost savings with diesel is $0.03/mile, so $3000 per 100,000 miles. I realize there are a TON of other ways to figure this, but for me, this is unloaded "average" driving. Cost increase between the trucks was over $8000 increase for diesel, with similar options, but we will figure $8000 just to figure mileage.

So $8000 would require 260,000 miles (@ $0.03/mile) to break even, just at "standard fuel costs". Towing rates, aren't much different from what I have been reading, still roughly a 4 MPG difference, so that still equates to $0.03/mile. I have had 0 issues pulling my trailer, and the power is adequate for what I need. If I averaged 26,000 miles/year, which I would say I will be under, then it would take me 10 years to break even on the vehicle. Being I haven't owned a vehicle longer than 7 years, I won't reach the break-even point, even keeping this 10 years.

With all this said, if I towed over 15,000 miles/year, or my trailer was 9,000+ pounds, I would have been even more interested in the diesel vs gas, or if diesel was consistently lower per gallon than gas. You have to look at your individual needs to really see the difference between the two, but that's a LOT of miles to just break even, without considering maintenance OR if you having something really go wrong, diesel parts cost more.

So, right now, I'm ok with my 11.7 MPG, and I'll get it over 12 MPG average for unloaded driving with tire pressure changes, and just running a MPH less.

So, roughly $0.03/mile difference at the current national average of fuel.

fjtort2 · July 10, 2017

So many people complain about the gas vs. diesel and lower MPG. I'm currently at 15,000 miles with my 2016 (having it for 8 months). Average (hand calculated) life is 11.7 MPG, with towing, city, empty driving, and the dash shows me at 11.3 MPG. I drive downtown Louisville daily, 6 miles to work, and 6 miles home. I was taking surface streets but have switched to the interstate, and am getting 1 MPG better average on my commute. I have adjusted tire pressure as well, run 50 in the front and 60 in the rear, and have gotten 1 MPG better, increasing when I tow. This is playing with pressure and speeds, and a LOT of my driving hasn't been very conservative, so my overall average should increase.

I have now towed my toy hauler (7500 pounds fully loaded) 3 times, a total of maybe 2000 miles out of the 15,000 I have driven (average fuel consumption has been 7-8 MPG). I have hauled roughly 1,100 pounds (two motorcycles, two bicycles, restraints) 2500 miles. So roughly 10,000 miles of my driving has been unloaded travel. I typically average 20,000 miles a year driving. I typically drive the speed limit to 5 MPH over unloaded, and when towing, usually 65 MPH max, which gives me 1-2 MPG better than 70-75 MPH.

Later this summer I will be towing the toy hauler from here to Montana and back, so that will be roughly 4,000 miles of driving when done. I'll be curious of my consumption, and I plan to run 65 MPH most of the time to save a bit of fuel.

I wanted the diesel, but it just didn't pay off to get it. Diesel here is still more expensive than gas. I tried to do a lot of math to determine my cost and which might be better, and it did not pay off to buy the diesel. Here is what I used to compare my math. Being that I do mostly unloaded driving, I feel I have to look at that first (although it really doesn't matter, seems the spread for loaded/unloaded is 4 MPG across the board)

Diesel 14 MPG city/18 MPG highway (this is what I searched, and I realize some people get better, but this is what I was seeing as average, and I will give it the benefit of the doubt and give it an average of 16 MPG over city/highway)

Gas 10 MPG city/14 MPG highway (this was what was reported, and since owning the gas, what I experience as the average, so I will say 12 MPG average, since I was close to that above)

4 MPG spread

DEF Fluid is 1.25 gallons/100 gallons of diesel. Def Fluid is $6/gallon, so $7.50/100 gallons of diesel.

For simple math and figuring out the difference, we will use these average nationwide prices, and 100 gallons to figure out the cost difference.

$2.25/gallon for gas

$2.50/gallon of diesel

Gas = $225 for 1200 miles = $0.19/mile

Diesel 4MPG spread (plus DEF) = $257.50 for 1600 miles = $0.16/mile

$.03/mile = $3000/100,000 miles

This is again, quick easy math, and rough figuring, and ONLY looking at fuel cost difference. Average cost savings with diesel is $0.03/mile, so $3000 per 100,000 miles. I realize there are a TON of other ways to figure this, but for me, this is unloaded "average" driving. Cost increase between the trucks was over $8000 increase for diesel, with similar options, but we will figure $8000 just to figure mileage.

So $8000 would require 260,000 miles (@ $0.03/mile) to break even, just at "standard fuel costs". Towing rates, aren't much different from what I have been reading, still roughly a 4 MPG difference, so that still equates to $0.03/mile. I have had 0 issues pulling my trailer, and the power is adequate for what I need. If I averaged 26,000 miles/year, which I would say I will be under, then it would take me 10 years to break even on the vehicle. Being I haven't owned a vehicle longer than 7 years, I won't reach the break-even point, even keeping this 10 years.

With all this said, if I towed over 15,000 miles/year, or my trailer was 9,000+ pounds, I would have been even more interested in the diesel vs gas, or if diesel was consistently lower per gallon than gas. You have to look at your individual needs to really see the difference between the two, but that's a LOT of miles to just break even, without considering maintenance OR if you having something really go wrong, diesel parts cost more.

So, right now, I'm ok with my 11.7 MPG, and I'll get it over 12 MPG average for unloaded driving with tire pressure changes, and just running a MPH less.

So, roughly $0.03/mile difference at the current national average of fuel.

Excellent post! The only thing you have to do to a 6.0 is add fuel. Rock solid platform. Nothing to worry about down the road. Love mine.

i82much · July 10, 2017

My math was simple - how many inches off the ground is the DEF tank? Answer - not enough to take it hunting in north Idaho. Gas truck it is!

Cowpie · July 17, 2017

The diesel vs gas thing has a lot to do with fuel costs regionally. I normally don't run out to PA much with my semi truck, but if I had to pay for diesel fuel what folks in PA do, I would never get a diesel. Just ran a load to Bethel, PA and jumped up to Williamsport and grabbed a load back and diesel price is just plain criminal. Even with my commercial discounts, diesel price was criminal. I still have a gasser 2500 simply because I don't have a need for diesel version. PA fuel would cost me $2.60 a gallon (after $.45 cent commercial discount from the normal $3.06 pump price a gallon) compared to crossing back into OH and getting it for $2.05 a gallon after $.43 commercial discount off pump price. I fueled in OH before running thru PA and fueled in OH later when I came back.

The problem is, some states tax diesel like only commercial heavy trucks use it, and it really blasts the average auto and pickup owner to fill up with diesel. ULSD diesel fuel market price is not much different from Gasoline market price. Both are hovering around $1.59 now. States play their silly little games with fuel tax and mess things all up. If state fuel taxes were similar for all fuels, diesel would have an edge in cost benefit.

Now, due to IFTA, I still have to pay fuel tax on all fuel that I use in PA, even though I bought it in OH, but still actual fuel cost to me in OH was over 40 cents a gallon cheaper than PA. That is sure one state I will continue to avoid as much as possible.

firerescuef2 · July 24, 2017

I just got back from a 200 mile trip, driving normally. Trip did include a drive up a mountain pass. I got 17 combined hwy/city. Not too bad for me. I have a diablo sport tune and a high flo air filter. Other then that I'm stock.

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2016HD · July 24, 2017

I just got back from a 200 mile trip, driving normally. Trip did include a drive up a mountain pass. I got 17 combined hwy/city. Not too bad for me. I have a diablo sport tune and a high flo air filter. Other then that I'm stock.

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How much of a difference did the Diablo tuner make for you? Thanks.

fjtort2 · July 25, 2017

How much of a difference did the Diablo tuner make for you? Thanks.

Don't mess with a "box tune" Get a custom tune for your 6.0! Thank me later!

firerescuef2 · July 25, 2017

How much of a difference did the Diablo tuner make for you? Thanks.

It made a big difference for me. Seems to have a lot more low end torque. And the gears wind out a lot faster. I'm assuming because of the increased horsepower. It definitely increased the smiles per gallon. And a few mpgs as well!

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firerescuef2 · July 25, 2017

Don't mess with a "box tune" Get a custom tune for your 6.0! Thank me later!

Just the "box tune" was a big wake up. If you do some reading you can do some data logs and fine tune it for optimum results. That's what I personally did after many hours of reading the diablo forums

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Cowpie · July 27, 2017

I just got back from a 200 mile trip, driving normally. Trip did include a drive up a mountain pass. I got 17 combined hwy/city. Not too bad for me. I have a diablo sport tune and a high flo air filter. Other then that I'm stock.

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Yeah, just did a short trip myself. I-80 rolling hills, 190 miles each way to Omaha including some running around down town Omaha, and some 15+ mph cross winds. I got about 16.8 for the entire trip with my 6.0. All stock except muffler and next size up BFG KO2's. No tune. About 95F and AC running the entire time. 4 people on board with some gear.

sdeeter19555 · July 27, 2017

Yeah, just did a short trip myself. I-80 rolling hills, 190 miles each way to Omaha including some running around down town Omaha, and some 15+ mph cross winds. I got about 16.8 for the entire trip with my 6.0. All stock except muffler and next size up BFG KO2's. No tune. About 95F and AC running the entire time. 4 people on board with some gear.

Did you account for tire size increase? If not, you are traveling further than odometer is registering...

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Cowpie · July 27, 2017

Actually, the tires put the speedometer/odometer dead on. Stock rubber was off.

Dale L · July 27, 2017

Actually, the tires put the speedometer/odometer dead on. Stock rubber was off.

With mine the stock tires have the speedo spot on with the GPS (Garmin)

Cowpie · July 27, 2017

Yeah, I compared my stock and next size up to two different GPS's. The stock had me going actually 1 mph less than what the speedometer said and the next size up matched the speedo to the GPS exactly.