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  1. #1
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    Default MPG for a 5.3/6 speed Sierra 4X4 with a 3.08 rear axle ratio?

    Does anyone know the mpg you can get for 2010 or 2011 Sierra 4X4 with the 5.3/6 speed automatic transmission with a 3.08 rear axle? Thanks

  2. #2
    Legend

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    At 60 mph-pure hy with cruise control on- you should get an honest 20-22 mpg.
    At 65 mph-pure hy-18mpg-20 mpg
    At 75 mph- pure hy- 16-17 mpg
    In pure city/suburban stop and go-10-13 mpg tank averages are about right-the tall gearing doesn't make any difference in stop and go driving, but it helps hy mpg a bit.
    Most folks in mixed driving will get 13mpg tanks- but on hy trips will get about 17-18mpg tanks
    Charlie
    PS I would guess you will turn maybe 1500 rpms at 60 mph-top gear??
    My 98 Suburban 2wd-5.7 1/2 ton gets an honest 21 mpg on long hy trips averaging 62 mph-I turn 1700 rpms-your more modern vehicle could get 1-2 mpg better hy despite the 4x4-at 70 mph you might get 19mpg
    Last edited by phoebeisis; 08-13-2011 at 11:28 AM.
    1998 suburban-
    1/2 ton

    199500 miles
    River
    Ridge,LA

  3. #3
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    Quote Originally Posted by phoebeisis View Post
    At 60 mph-pure hy with cruise control on- you should get an honest 20-22 mpg.
    At 65 mph-pure hy-18mpg-20 mpg
    At 75 mph- pure hy- 16-17 mpg
    In pure city/suburban stop and go-10-13 mpg tank averages are about right-the tall gearing doesn't make any difference in stop and go driving, but it helps hy mpg a bit.
    Most folks in mixed driving will get 13mpg tanks- but on hy trips will get about 17-18mpg tanks
    Charlie
    PS I would guess you will turn maybe 1500 rpms at 60 mph-top gear??
    My 98 Suburban 2wd-5.7 1/2 ton gets an honest 21 mpg on long hy trips averaging 62 mph-I turn 1700 rpms-your more modern vehicle could get 1-2 mpg better hy despite the 4x4-at 70 mph you might get 19mpg
    Thanks for the response. Boy, I didn't realize the 5.3/6 speed does so poorly in stop and go city traffic for mpg. 10-13 mpg isn't very good. That's where I do most of my driving. My current truck, a 2000 Sierra 2500 with the 6.0L V8 and old 4 speed gets about the same in stop and go traffic too. Would the 4.8/4 speed or even the 4.3/4 speed be any better in the city?

  4. #4
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    You gotta remember .. It's a 3 Ton Truck....It still get better MPG then a Dodge Durango and many other SUV's. And it can carry a house (almost)

    It's also in your driving...
    08 Z71 Avalanche Mods to date: K&N CAI,Hellwig Swaybars and End Links, Corsa Sport Exhaust, Superchips Programer,IPCW LOF & 3rd brake light and tails, AMI Gas door,Show Hooks and Door locks, Enkei Wheels, with Pirelli tires, StreetScene Bowties, Grant Steering wheel,Muth signal mirrors,SSBC Big Brake kit,Huskyliner Mug gards,Floor mats and Hood shield, McGard Lug nuts and locks, Bedrug, Cervini's Ram Air hood,35watt HID Fog lights, Sylvania bulbs all around ZXE's Highs and Lows, WhiteNight Back up lights,Sirius and HD Radio, SnugTop sitting on deck now Got a Softopper on now,Tempress Boat Hatches.... New Bilstein shocks are on... New Mods coming soon..... X

  5. #5
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    The recent 5.3-driven the same way- is MUCH better FE wise than the 2000 6.0.
    I WAS JUST GIVING AVERAGE SORT OF NUMBERS-I am a mpg fanatic.
    Driven the same way-and if your 2500 is a 4x4- you will get 2-3 mpg better city with the 5.3 six speed.
    You will also get as much as 3-4 mpg better hy.
    A current 5.3 -in same sort of truck(but it will be lighter than a same same 2500 6.0) GETS MUCH BETTER FE THAN A 6.0 2500.
    If your 6.0 2500 is a 4x4 you will get DRAMATICALLY BETTER FE with a 2011 5.3 .
    Dramatically better means 2-3 city and maybe 3-4 hy.
    No one brags about a 6.0 FE(except to say it is better than a 454)- lotta folks brag about the 5.3's FE.

    Forget about the 4.8 or the 4.3 for FE.The 5.3 matches them in FE(or is so close it doesn't matter) and is BETTER in every other way.
    The only reason to choose a 4.3 or 4.8 over the 5.3 is they are cheaper to buy.Now cheaper to buy is a decent reason- but if you have the extra $$-always go 5.3 over those 2. GM puts lots of engineering(and $$) into maxing the 5.3 in respect to FE.Nothing wrong with the 4.8 4.3 but they are there to keep down cost-a good reason.
    Charlie
    PS Like Enkeiavalanche says- the driver makes A HUGE DIFFERENCE in actual FE numbers.
    1998 suburban-
    1/2 ton

    199500 miles
    River
    Ridge,LA

  6. #6
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    Quote Originally Posted by phoebeisis View Post
    The recent 5.3-driven the same way- is MUCH better FE wise than the 2000 6.0.
    I WAS JUST GIVING AVERAGE SORT OF NUMBERS-I am a mpg fanatic.
    Driven the same way-and if your 2500 is a 4x4- you will get 2-3 mpg better city with the 5.3 six speed.
    You will also get as much as 3-4 mpg better hy.
    A current 5.3 -in same sort of truck(but it will be lighter than a same same 2500 6.0) GETS MUCH BETTER FE THAN A 6.0 2500.
    If your 6.0 2500 is a 4x4 you will get DRAMATICALLY BETTER FE with a 2011 5.3 .
    Dramatically better means 2-3 city and maybe 3-4 hy.
    No one brags about a 6.0 FE(except to say it is better than a 454)- lotta folks brag about the 5.3's FE.

    Forget about the 4.8 or the 4.3 for FE.The 5.3 matches them in FE(or is so close it doesn't matter) and is BETTER in every other way.
    The only reason to choose a 4.3 or 4.8 over the 5.3 is they are cheaper to buy.Now cheaper to buy is a decent reason- but if you have the extra $$-always go 5.3 over those 2. GM puts lots of engineering(and $$) into maxing the 5.3 in respect to FE.Nothing wrong with the 4.8 4.3 but they are there to keep down cost-a good reason.
    Charlie
    PS Like Enkeiavalanche says- the driver makes A HUGE DIFFERENCE in actual FE numbers.
    Thanks again for the response. You have great information. I like the 5.3 but as it's a $2 000 option if you buy it here in Canada, that's where I live, on a new truck. I'll have to see if I can find a used 2010 with the 5.3 and 6 speed combination. Is there any other way to improve mpg? I've heard that tonneau cover helps with mpg? Any truth to that?

  7. #7
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    Not much- a cover cost mpg in the city-extra weight(tiny decrease hard to measure)- but it could very slightly-tests I've seen show no benefit to small-1/2 mpg- hy improvement.
    Many folks CLAIM 2 mpg better but that is wrong. The open bed-tailgate CLOSED- aero wise acts like it is already covered-yeah it doesn't make sense, but all tests I've read say keep the tailgate closed, and just get a cover to protect your tools- it won't net improve mpg-city decrease and hy increase cancel one another.
    Bottom line-OEM engineers have pretty much maxed the 5.3 for FE- CAI fancy exhausts-waste of $$ for PART THROTTLE FE.
    Modifying driving habits- Pulse and glide in city traffic and staying under 70 mph will improve fe maybe 15% without costing more than 2-3% in trip time.
    Charlie
    PS With the cruise control set to 62 mph you could get 21mpg
    1998 suburban-
    1/2 ton

    199500 miles
    River
    Ridge,LA

  8. #8
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    Quote Originally Posted by phoebeisis View Post
    Not much- a cover cost mpg in the city-extra weight(tiny decrease hard to measure)- but it could very slightly-tests I've seen show no benefit to small-1/2 mpg- hy improvement.
    Many folks CLAIM 2 mpg better but that is wrong. The open bed-tailgate CLOSED- aero wise acts like it is already covered-yeah it doesn't make sense, but all tests I've read say keep the tailgate closed, and just get a cover to protect your tools- it won't net improve mpg-city decrease and hy increase cancel one another.
    Bottom line-OEM engineers have pretty much maxed the 5.3 for FE- CAI fancy exhausts-waste of $$ for PART THROTTLE FE.
    Modifying driving habits- Pulse and glide in city traffic and staying under 70 mph will improve fe maybe 15% without costing more than 2-3% in trip time.
    Charlie
    PS With the cruise control set to 62 mph you could get 21mpg
    I've read that when the new 1500 series debuts in 2014, the 5.3 is expected to get 4 valves per cylinder over the current 2. That might improve mpg a bit. I wish they would update the 4.8 or 4.3 and at least offer them with the 6 speed found on the 5.3. Makes no sense as to why the 4 speed is still standard on these engines when GM's major competitors Dodge, Ford, and Toyota all carry 5 and 6 speed automatics as standard equipment. My guess is that the 4.8 and 6 speed combo would probably equal or surpass the 5.3 in mpg. Then GM wouldn't be able to charge extra for a 5.3.

  9. #9
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    Yes it is probably intentional-using the 4 speed makes them a tiny bit less costly to build, but it allows GM to put a premium price on the 5.3.
    The 4.8 now has cylinder shutdown feature-making it more desirable than the 4.3

    4 valve heads -
    Will it retain pushrods??In the very old days I think there were racing motorcycles with pushrods and 4 valve heads.
    Charlie
    Last edited by phoebeisis; 08-15-2011 at 08:13 AM.
    1998 suburban-
    1/2 ton

    199500 miles
    River
    Ridge,LA

  10. #10
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    [QUOTE=phoebeisis;393676]Yes it is probably intentional-using the 4 speed makes them a tiny bit less costly to build, but it allows GM to put a premium price on the 5.3.
    The 4.8 now has cylinder shutdown feature-making it more desirable than the 4.3

    4 valve heads -
    Will it retain pushrods??In the very old days I think there were racing motorcycles with pushrods and 4 valve heads.
    Charlie[/QUOTE

    Does the 4.8 have cylinder shutdown in this year's Sierra model?

    I found a couple of used 2008 Sierra 2500 with the 6.0 V8 and 6 speed. Do you know how good/bad these things do in the city for mpg?

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