19-20 mpg possible 6.0 gas?

Rvduck · February 1, 2017

The 6.0 is a great motor and is not a epic in any way. One of the most long lasting and most reliable motors out there and pulls stronger than the other manufacturers despite their so called higher HP ratings. But that is why it is the entire drivetrain for the 6.0 that really shines.

Hear! Hear! I certainly agree with this post and anyone who would say that yesterday's big blocks were more powerful is a dreamer. I am talking stock engines. My 1988 F250 with the so called amazing 460 was equal to any Chevy 454 of the day and that truck weighed a full ton less than my new beast. Empty driving very carefully I could get 8 miles to the gal and towing a light little Fifth wheel from Canada to Disneyland , I averaged 6 miles to the US gal. When I upgraded to a 94 powerstoke, my milage doubled. Power wise, my new 6 would blow the doors off that 460 pig. Keep the fairy tales coming about the old big blocks, I enjoy a good belly laugh!

TRKLGND · February 2, 2017

My 2004 2500HD crew cab 4x4 6.0L with 4:10s got 11.5 around town, 14 highway and 8.5 towing a 5000lb boat. And I do drive like an old lady.

Doug Rosewood · February 5, 2017

Friend of mine and I was talking the other day. He has an early 15 2500 with the 6.0 and only thing he's done to it is put exhaust on it. Truck is completely stock, and torsion bars are in stock locations yet. Truck has just under 16,000 miles on it. Guy SWEARS he get 19-20 mpg on the open road with it. I know these trucks were standard with 4.10 gears, but could it be possible the early ones have 3.73? He says its 4.10 gears, but I just don't see how 19-20 is possible. My truck's best was 12.4 in completely stock trim with absolutely no modifications.

I know there is already a MPG post here somewhere, but this just seems too far-fetched for me to believe.

according to my dash, the best average I've had is 21, I drive like I'm 90 though..

Cowpie · February 5, 2017

Not sure the age thing has anything to do with it. My dad was busting that sound barrier with his pickup well into his 80's. More than once he had to do to one of those defensive driving classes to avoid losing his license for speeding. That, and years of commercial driving, might be the chief reasons that I drive a little more moderately.

j-ten-ner · February 5, 2017

Nothing wrong with driving a truck and having an eye on the fuel economy.

One can try to get the best out of it but there are limits, set by the vehicle/engine combination.

I enjoy driving a truck. I also drive in a moderate/confident way.

Only once in a while I have to "give the ape some sugar".

Not street racing, but a passing maneuver every now and then.

I'm wasting fuel already, just by driving a truck for pleasure.

Although I recently started to use him for work and the fuel is paid for, I still try to keep it down.

so long

j-ten-ner

Cowpie · February 5, 2017

Yeah, I get to write off fuel, repairs, etc on my 2500 as well, along with depreciating the cost. But I still try to get the best economy I can. Can't avoid the higher fuel usage because of the vehicle, but it is required for the tasks that it has to do. A 1500 isn't going to cut it. And maybe it is just me, but I like driving the 2500 overall compared to a 1500. Not sure if it is just the more firm truck feel or something else. And so true, once in a while one has to "put a wiggle in it" to get on around someone or some other reason.

magnum74 · February 5, 2017

A 1500 isn't going to cut it. And maybe it is just me, but I like driving the 2500 overall compared to a 1500. Not sure if it is just the more firm truck feel or something else.

I did make the mistake of going back to a 1500 regretted it almost instantly. I'm not knocking 1500's or saying real men drive HD's and BS like that but a GM HD 6.0 has to be the one of the best examples of efficient utility and performance on the market. When I say efficient I don't mean fuel economy but as a whole an amazingly well balanced drive line for it's purpose. It outperforms a Ram 6.4 any day of the week (I had one for almost 60,000 miles so I know first hand) on the flat or up a hill and handles much better with 1000lbs+ in the box or on the hitch than a 1500 does. The driveline works much better and is happy to hold or shift gears even with tow/haul off.

I've been using my trucks for business purposes in the oilfield and remote sites for 15 years and an 87 octane HD is the simplest and most useful thing operate and maintain especially in cold weather. GM just happens to have the best balance on the market. The Ford 6.2 is likely a very good option too but no gas HD is going to touch a diesel pulling heavy on a grade unless you start doing silly things them.

I've never been able to get much better than 15mpg (hand calculated, no magic meter reading based on 25 miles of driving haha) on any 6.0 I've had but the difference in how the HD handles weight and how well the driveline works from the factory makes it a much better option for me. I think anybody who is at the threshold to make them ponder 1500 vs. HD would probably be happier with a HD.

Even though the L96 looks "small" on paper in real life it performs and being able to get a true 15mpg is impressive to me. I also don't remember old big block trucks putting 360/380 either lol.

Cowpie · February 5, 2017

Yeah, it is a package deal. Looking at numbers on a glossy brochure and such just doesn't give an accurate picture sometimes. I never look down at the 1500's or who buys them. It is purely a matter of what one needs to do something. Given that the GM 2500 lineup is almost identical in price with the equivalent 1500 lineup, the 2500's with the 6.0L seem to offer the best overall value for the dollar, even with the lower fuel economy, while still offering some of the best overall capability and reliability.

free88 · July 20, 2018

I know this is a bit old thread, but I just wanted to say that a claim of 19-20mpg is possible on the 6.0L with 4.10 gears and stock tires. You would have to drive like an old lady and go about 45 mph, unloaded, calm, flat, etc. Somewhere around that speed is a sweet spot, where I do see the instant mpg stay above 20mpg consistently. I am not saying I have verified this mpg over a tankful, but to me at least it does seem possible to get those numbers at that speed.

I havent put the miles you guys have on my 2018 2500 6.0, but so far it seems to be about 12-13 city, 15-16 highway (65-70 mph). Can you possibly get 17-18 on the highway? Maybe, but not at those speeds. You would have to be closer to 55-60 mph.

As others have said, the 6.0L is not a wow engine. There is nothing super advanced with it, no cyclinder deactivation, no super chargers, etc. Even though it shares nearly the same HP/TQ numbers with the current 5.3L and close to the same displacement as the 6.2L, the 6.0L is a very different engine than both of those. Its an engine/trans setup for reliability and durability, first and foremost. While the similar HP/TQ 5.3L is also a fantastic engine, I would not look to tow big with it and/or for a long tow. Its not going to have that long term reliability and durability if you bog it down day in, day out. The 6.0L will. I disagree with others that the 6.0L is underpowered, and I dont wish for more power with it. I think people just get spoiled, honestly. Its the knowledge that something else more powerful exists, and, therefore, now yours isnt powerful enough. Thats just macho BS. The 6.0L has abundant power for its intended use, and at least on par vs direct competitors in standard stock configs in terms of real world power to the wheels.

alaskaguy2019 · July 20, 2018

On 1/21/2017 at 5:17 AM, Cowpie said:

Never have figured out what driving like an old person is. Is that obeying the speed limit? Well, given that speeding tickets are just a money cost and a nuisance to many, if you have a commercial drivers license, all it takes is 2 tickets of 10 mph over the speed limit in a year to loose your license (and your livelihood) for 6 months. Yes, even in a personal vehicle and not just during commercial driving. Look it up in the regulations. That would cause my entire business to fold up and be no more. Many other violations that are very minor to the average driver, can mess up bad the license of a commercial driver.

anyhoo, the 17.5 mpg I got was in rolling hills of Missouri and Iowa. Running about 65 most of the time, which was the speed limit over a large portion of the drive. And Hwy 61 and 65 in Missouri can hardly be considered "flat" for much of it. The mpg was for the 400 mile average and the overall trip average. I did make a mistake though..... stated 17.5 it was actually 17.4. Memory not as good as it used to be. It could be that I have over 5 million miles of commercial driving under my belt and have learned a few things about how to get decent fuel economy from any vehicle. My Cadillac CTS the same type of thing. EPA highway is 25 mpg, I can get 27-28 frequently. My commercial semi truck, lifetime average is 7.93 mpg over 642,000 miles. That is well over 1 mpg better, in fact almost 2 mpg better, than the national class 8 truck average for the same type of trucking. Just skilled, not driving like an "old person". That 1 mpg better average for most wouldn't mean anything, but for a commercial heavy truck, that equates to about $8000 a year is fuel savings.

And lifetime average for the 2 years I have had this 2500, including some local short distance towing, lots of hauling, on highway, in town, daily rural gravel roads of a minimum of 2 miles one way, off road on the property checking things and fence line and some work, everything.... the average lifetime mpg for my 2500 is about 13.5 mpg. The question is not about the vehicle, but the skill of the driver that really one should be asking themselves if they can't get above 12 mpg with a 2500 6.0L. I could even get 16 mpg on my '98 2500 with a 454 on some road trips.

i get about 16-17 MPG average on a 300mi. commute i do every two weeks here in Alaska. That is through some steep mountain passes and nothing but hills, only one stretch of 10 mile that is flat. So with that type of driving and still getting an overall average of 16-17, i totally agree with you that its on the part of the driver to get the most MPG possible.

SierraHD17 · July 20, 2018

My 17 started life with 3.73s and the entire drive home ( around a 400 mile trip) I averaged around 18 mpg. The truck actually could recreate it provided it was calm and no head wind. The drive home I had a tail wind but it was not strong so although it helped no doubt the truck still did it. Then I leveled it, added bigger rubber, tuned it and did 4.56 gears hahahaha. The 4.56s honestly recouped mileage from the tires and level with the lame ass 3.73s.

The saddest thing about 3.73s was the sorry sack 9700 lb tow rating it gives the truck.. especially one some dummy ordered the fifth wheel prep package on as well as the 3.73 lol.

swathdiver · July 21, 2018

On 1/27/2017 at 9:48 PM, sdeeter19555 said:

I've driven cross country more than I can begin to count...almost all pickup, a little HD truck. Driving the speed limit or even under will make you better time, less stressful driving, and just more enjoyable ride. I can't begin to tell you the number of trips I had where I would mentally mark a unique car or truck flying by...more than once I'd pull into the hotel at the same time they did (and they have passed me a dozen times in the process)...not to mention I was getting about the best mileage whatever truck I was driving would get because of the way I was driving...

Same here, used to see it all the time up and down the Eastern Seaboard, see it every trip we take to visit my folks, knuckleheads passing us 3,4 and 5 times and we get off the same exit at the same time. I always use the cruise and have slowed down, the difference between 70 and 75 mph for sixty miles is about 90 seconds and a gallon of fuel. I can wait!

16 hours ago, free88 said:

As others have said, the 6.0L is not a wow engine. There is nothing super advanced with it, no cyclinder deactivation, no super chargers, etc. Even though it shares nearly the same HP/TQ numbers with the current 5.3L and close to the same displacement as the 6.2L, the 6.0L is a very different engine than both of those.

The L96 is a Gen IV engine with VVT and is/was FlexFuel. It replaced the LY6 in 2010 and is a near bullet proof motor. A tune wakes them up and makes them more fun to drive and efficient. Same for the transmission.

free88 · July 21, 2018

I wish there was more mpg data on the 2015-2019 6.0L/3.73. What little data is out there leads you to believe there is practically no economy advantage with the 3.73 vs 4.10 on the 6.0L, which is disappointing. For some, dropping down to 9500lb-ish towing is not really a big deal, especially if you could squeeze another 1-2 mpg out of it.

SierraHD17 · July 21, 2018

The trucks are so pathetic with 3.73s it's annoying though lol. I mean all the thing does is shift and even with stock tires it wasn't particularly something I would consider desirable. These engines make no power nor really want to cruise below 2000 rpm any significant amount and never have. The L92 heads exaggerate that problem and always have. It's not hard to compare considering the 11 to 14 trucks are identical minus sheetmetal so you can use those as a comparison and there is no real significant advantage.

Not to mention the 15 and newer trucks don't come with 3.73s to the normal consumer so it's kind of irrelevant for the few of them there is out there.

Cowpie · July 21, 2018

On 7/20/2018 at 8:22 AM, free88 said:

I know this is a bit old thread, but I just wanted to say that a claim of 19-20mpg is possible on the 6.0L with 4.10 gears and stock tires. You would have to drive like an old lady and go about 45 mph, unloaded, calm, flat, etc. Somewhere around that speed is a sweet spot, where I do see the instant mpg stay above 20mpg consistently. I am not saying I have verified this mpg over a tankful, but to me at least it does seem possible to get those numbers at that speed.

I havent put the miles you guys have on my 2018 2500 6.0, but so far it seems to be about 12-13 city, 15-16 highway (65-70 mph). Can you possibly get 17-18 on the highway? Maybe, but not at those speeds. You would have to be closer to 55-60 mph.

As others have said, the 6.0L is not a wow engine. There is nothing super advanced with it, no cyclinder deactivation, no super chargers, etc. Even though it shares nearly the same HP/TQ numbers with the current 5.3L and close to the same displacement as the 6.2L, the 6.0L is a very different engine than both of those. Its an engine/trans setup for reliability and durability, first and foremost. While the similar HP/TQ 5.3L is also a fantastic engine, I would not look to tow big with it and/or for a long tow. Its not going to have that long term reliability and durability if you bog it down day in, day out. The 6.0L will. I disagree with others that the 6.0L is underpowered, and I dont wish for more power with it. I think people just get spoiled, honestly. Its the knowledge that something else more powerful exists, and, therefore, now yours isnt powerful enough. Thats just macho BS. The 6.0L has abundant power for its intended use, and at least on par vs direct competitors in standard stock configs in terms of real world power to the wheels.

Well, like I stated, it did pull 17.5 average running 65+ on a 1000 mile trip a couple of years ago.

I will mix this in also.. while I generally have gotten 14 average for all miles.... highway, city, rural gravel, hauling etc.... I also seem to average about 11 mpg on E85. Sure that sounds lousy, but it actually isn't.

At 14 mpg for regular E10 going for about $2.62 a gallon right now near me, that equates to about 18.7 cents a mile fuel cost.

At 11 mpg for E85, which is $1.82 near me, that equates to about 16.5 cents a mile fuel cost. A 2 cent per mile savings. That is why my 2500 has been on E85 for almost a full year now. Not that I have some sort of love affair with ethanol, but the simple idea that my pickup can use it and it offers a much better value.