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2008 Pontiac G8



  • eliaselias Posts: 1,830
    murph, gas is $1.80 per gallon.
    if saving $ is your goal, maximizing mpg is probably not the best strategy currently.
  • tayl0rdtayl0rd Posts: 1,938
    Yes, either one of those could (and probably will) destroy your tranny if you don't get it fixed soon. A loose flywheel could probably destroy your engine, too, since it's connected directly to the crankshaft. The excess vibration/imbalance could potentially crack/snap the crankshaft.
  • 4) 300 mile trips maximum MPG is 25.5 @ ~ 65MPH - 68MPH highway. The MPG does drop quite a bit in city driving but strictly highway is excellent.
  • gas is mos likely not staying at $1.80, in fact where I live it is still at leat $2.00.

    Thanks fo the info.
  • rayainswrayainsw Posts: 2,476

    We know that my Corvette was rated at 15 \ 25.
    [ Under the current rating scheme – not the one, in effect in 2007 ]

    And the G8 GT is rated [ under the same scheme ] as 15 \ 24.

    ** BUT ** that G8 GT highway rating is achieved with use of AFM.
    [ a.k.a. DoD ] The Corvette’s LS2 does not have AFM.
    [ Edit: My understanding is that AFM will not engage
    when in Sport \ Manual mode - ever. ]

    What I expect is that instead of achieving only 1 less MPG in ** MY ** typical ex-urban highway cruising, I will see a drop of 2 or 3 or 4 MPG. When (semi-)legal I typically cruise at 70 to 75 \ 78. What I have read leads me to believe that at those speeds, AFM will rarely, if ever, activate. Though at 60 or 65 it will, assuming no headwind or upslope. My Corvette would return 27 or 28 or even a bit more, on long highway runs at those speeds, as a point of reference.

    I am driving this weekend to visit friends who live on the Florida Panhandle – and there are stretches of dead level ( just above sea level ) roads, straight for miles, with little traffic ( typically ) where I hope to experiment under near ideal & controlled conditions.

    Again – I will report the results when I return – next Tuesday or Wednesday, if all goes according to plan.

    Clearly, the G8 is much heavier than my ‘Vette. At highway speeds, it has a much larger frontal area & is less aerodynamic. That, plus higher RPM lead me to the speculation \ guesses above.

    - Ray
    Cautiously optimistic.
  • paopao Posts: 1,867
    I see gas going lower.....1.50 in parts of VA right now....1.90 around the DC area and falling daily...if you are concerned about fueling the car...then its not for you IMHO.....if you want to maximize MPG....get one of the 4 bangers or the 6 Cyl VVT engines out in various models these days...
  • not really interested in the "4 bangers".....I want a confortable highway cruiser that I can put the 3 kids in the back when needed. My concern is if gas heads back up to $3 or higher I don't want to be stuck with a car that gets poor mileage.
  • rayainswrayainsw Posts: 2,476
    What is your definition of
    "poor mileage" ????
  • circlewcirclew Posts: 8,250
    Have a safe and satisfying drive ans a Happy Thanksgiving! Best of luck with your new ride! It sounds fantastic!

  • i would like to at least get 25 mpg. I have a smaller car now but want something larger...spend a bit of time each week on the road. The GT is very tempting.
  • paisanpaisan Posts: 21,181
    My guess is that if you are concerned about $3.00 gas that you should probably not be looking at anyV8 engined cars. If your budget is so tight that a change in gas prices to $3.00 will seriously impact you, really a less expensive car taht gets better milage should be at the front of your shopping list.

    Not trying to be mean, but trying to be realistic.

    Subaru Guru and Track Instructor
  • paisanpaisan Posts: 21,181
    Also Ray, don't forget your car is new, so you won't see max MPG until you hit about 9k-10k miles on it. Modern cars take that long to get to max MPG.

    Subaru Guru and Track Instructor
  • white6white6 Posts: 588
    FWIW, my 08 GMC Sierra SLT shows AFM engaged when cruising at 70-75 mph on anything other than uphill terrain (or driving into a stiff headwind). I'm sure it weighs quite a bit more than a G8 GT and is significantly less aerodynamic to boot (plus heavy 20-inch wheels/tires). The AFM also kicks in at speeds as low as 38 mph. Of course, all this could be affected by final drive ratio; my GMC has a 3.73 rear gear (but only a 4-speed auto). Could be a situation where driving 73 instead of, say, 76 could make a noticeable difference.
  • The cylinder shutdown makes a big difference. In general it won't be activated at 70+ MPH except during slight downgrades. I really helps when active. I have put a total of 12 k miles on two G8s (an 08 and a 09). The 25MPG figure is fairly accurate and it is hard to get better at a reasonable speed.

    Funny thing, I can coax 33-34MPG easy out of my C5 vette 6 speed Manual. It is even easy to coax good city mileage out of the vette by letting it lug in a gear too high. Nobody believes these numbers but I have proved it several times. I bettered a Toyota Matrix on HW MPG once after the owner challenged me.
  • circlewcirclew Posts: 8,250
    That's what less wind resistance and weight will do and the M/T driven right is just icing on the cake! Everyone should drive a 'vette!

  • eliaselias Posts: 1,830
    mrpushrod is heroic to me and I give him bonus credit for hypermiling his vette - destroying an entire set of gatorbacks at 44 psi just to save 46 cents on fuel to dust that gas hog Matrix.
    (if you intentionally overinflate&use the inflato-spare, and drive on the painted line on side of
    road, that saves another .00014 mpg.)
    just sayin.
    seriously i would be drivin a vette but gotta have the back
    seat so i be driving the goat-naro 05 gto, which will NEVER see 30 mpg.
    (i hypermiled it and it got 24.1 instead of 23.9.)
    but it can turn in a solid 21 along with considerable vettelike characteristics.
    i wanna try me a G8 V8 with stick.
    I'd even try a V6 G8 with stick.
    At this rate it seems like the only way that will happen is if that jet-leasing GM president Lyle Waggoner flies me to australia to take a test drive down under.
  • circlewcirclew Posts: 8,250
    Anyone who owns a 'vette is my hero. It's the only GM left I would buy.

  • paisanpaisan Posts: 21,181
    Is the vette even back in production? :)

    Top Gear actually did a test of a GT3 v. Prius. Where they drove the Prius on the track at petty much track speeds as fast as the Prius could do the circuit. Then they ran the GT3 at the same lap times/speeds as the Prius, which was considerably less than flat out. The GT3 turned a significantly BETTER milage than the Prius.

    Subaru Guru and Track Instructor
  • Ok, tires slightly overinflated but it is really easy to achieve 32-33MPG in the vette and better when trying hard. Personal record of 38.5MPG on a 150 mile trip (requires a truck though if you get my drift). The G8 would be a guzzler if not for the deactivation feature. We traded a town car (had lowest rear end ratio and dual exhaust) for the G8 and it did better than the G8 in our real world. But if your are a highway commuter averaging 65-70MPH believe my G8 number. It rarely fluctuates too.

    As far as GM goes, that is not true. I owned a 94 impala that I really liked that. I enjoy the G8. I test drove the CTS and STS, both nice cars. The STS was much better than I anticipated, especially for a family hauler. The CTS provides a nice ride/handling balance. I bet the V is a hoot but never got the pleasure. I have never been disappointed with a Northstar V8. DTS not my cup of tea though. My vette has about 30k miles on it, bought it new. It has a few rattles (removable roof and all) but it always puts a smile on my face. I rather the fun of a RWD than the steadiness of 4WD. Torque and RWD is essential for my dose of adrenalin. I drift the rear end on just about every spin I take it on. What other cars have a HUD???

    GM has made some good cars and trucks, they haven't been all bad. If they go under, there goes half the cars out there that still have gut wrenching torque.
  • paisanpaisan Posts: 21,181
    Well with Pontiac going the way of Oldsmobile, looks like we should be able get these G8s at a phenominal price. :)


    Subaru Guru and Track Instructor
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