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Fuel Saving GM Truck-Questions

Discussion in 'Uncategorized Threads' started by missalot, May 7, 2007.

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  1. missalot

    missalot TS Member

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    Do any of you have one of the new GM trucks that has the feature where the engine shuts down 4 of 8 cylinders in a no-load situation to economize? If yes, how much better mileage do you get? Does it still have the power when you want it? Do you like it?

    Thanks..don't trust what the dealerships tell me
     
  2. dverna

    dverna Active Member

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    I have a 99 Mercedes E430 (8 cyl sedan) and it has the variable cylinder technology.

    You cannot tell if it is kicking in or out - very smooth. I get 28 MPG highway with it. $5,000 option but with only 125,000 miles I doubt I have "broken even". I expect it will have negligible savings in city driving.

    Look at the expected savings and do the numbers. It may be "nice" but it may not have a decent payback.

    Don
     
  3. goose2

    goose2 Well-Known Member

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    I have a 07 suburban and a 07 avalanche with that feature in both. Here in Idaho I do not think that it helps that much. Only because of the hilly terrain. It seems that it is never in v4 mode. On a quick note. The avalanche will get 20+ mpg at 78 mph with air on most all the time. So with that said. Something they have done is helping the mpg. The suburban only sees 17 mpg. Must be from the added weight.
     
  4. Bob Hawkes

    Bob Hawkes Well-Known Member

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    Missalot, I also had my doubts on purchasing an 07 suburban. It seems to be a great vehicle so far, but I've only got 2,000 on it. You do not feel the 4/8 switching back and forth. If this motor fails, I would think it could take GM down. So I am sure it is well thought out and proven in their minds. Fuel economy seems decent early on. Good luck, Bob H
     
  5. W.P.T.

    W.P.T. TS Member

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    Cadillac had this feature on their cars a few years ago (early 70's) and the first thing the dealer did when anything went wrong with it was disconnect it and leave it that way ... They would say it was more trouble than it was worth and the difference in mileage wasn't what it was supposed to be so they just cut the wires and let run on all 8 all the time ... WPT ... (YAC) ...
     
  6. higun

    higun Member

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    Jan 29, 1998
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    Missalot,
    I bought a 2007 Suburban back in January of this year that has the feature you are asking about. So far it has been a great vehicle. Unless you watch the display or listen very closely you will never detect the change between 8 and 4 cylinders. There is always full power when you need it.
    My driving consists of about 75% highway and 25% city. As of today I am averaging 17.7 MPG. I have only 6085 miles on the vehicle now and most of that has been during the coldest months with occasional use of 4 wheel drive.
    I expect that my average MPG will increase over the less demanding summer months.
    I like the feature and believe that it gives me at least a 20% increase over the same vehicle without the feature.
    The 70’s were more than 30 years ago.
     
  7. chopperman

    chopperman Member

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    Feb 12, 2006
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    I have a 2007 Silverado crew cab with this feature. 11000 miles 15.6 miles per gallon.2005 got 16.9. Chris
     
  8. CalvinMD

    CalvinMD Well-Known Member

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    Location:
    Northeastern MD @ the top o the Bay
    Give it time before the final judgement...my 04 SuperDuty took over 35k miles just to break in with synthetic oil...it went from an average of 15.1 to 17.4 after reaching that point on a trip back to Maryland
     
  9. famill00

    famill00 TS Member

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    I drive an 07 Honda Civic. I get 42mpg on the highway. Hmmmm....I think its the economical choice. IF I need a truck I borrow one :)

    Forrest
     
  10. CalvinMD

    CalvinMD Well-Known Member

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    Always good to know a friend with a truck!
     
  11. load

    load TS Member

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    Jan 29, 1998
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    ya why dont you take 3 or 4 of your buddies to the next shoot with you
     
  12. ljutic73

    ljutic73 Well-Known Member

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    Location:
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    Going be taking delivery of a pristine '06 GMC Envoy Denali with the 5.3L HO V-8 with cylinder deactivation....put some demo miles on it the other day....it goes like hell with 300HP and I couldn't tell when the transition occured.
     
  13. jimx200

    jimx200 Member

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    The variable engine Cadillac came out in 1984 in the Seville. It was a lemon and pulled after 3 years. The resale on a car with this engine was terrible. These were also the years that GM put their diesels in the pickups...another badly engineered engine that cost GM (and owners) millions as they were replaced and then the replacement engine would die. What a fiasco from GM.
     
  14. halfmile

    halfmile Well-Known Member

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    Green Bay Wisconsin
    Watching this crap for forty years, the trend is to let the buying public be the test ground. If you get hosed they stall you till you can't stand it any more.

    I have to admit, when I started almost any car would not make a hundred thousand miles before the junkyard.

    Taking the lead out of the gas eliminated the yearly tune up. But tie rod ends with no grease fittings are way beyond stupid.

    Cadillac had some great lemons, I had a 4100 that ate 900 dollar head gasket jobs almost evry 2 years.

    I guess a new unproven that's cheaper to make is loved by management more than refining the good rliable stuff.

    HM
     
  15. alfermann66

    alfermann66 Member

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    I can only hope all of you guys who buy these gas hogs and think 17 or 18 mpg is good really have a need for them. My Frontier gets near 30 mpg with the cruise set 60-65 and will haul 1200 lbs. of shot home when needed and my friends '98 Silverado gets 22 mpg with the cruise set 60-65. When gas goes to $100 per gal., and it may, maybe the gimmicks will be worth the money and aggravation.

    Buz
     
  16. Bruce Specht

    Bruce Specht Well-Known Member

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    It sounds like the old Cadillacs that had 4,6, and 8. The car in theory only used 4 cylinders until more were needed. It didn't work then and I'd be carefull about buying old technology that was poor from the start. Thye ahad that technology in the late 70's and it went away.
     
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