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Pontiac Grand Prix: Real World MPG

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Comments

  • gxpjoeypgxpjoeyp Member Posts: 38
    Maybe the gas in wisconsin is lousy I dont know but I do know that I have always used premium/93 octane since the car was new,do the cruise thing on the xpway,dont hammer the hell out of it, who knows,but here in milwaukee we use that re formulated gas more expensive cause it burns cleaner so they say 75 miles north of me they use the "old" gas....GO STEELERS!!!!!

    GXPJOEYP
  • bubbaman999bubbaman999 Member Posts: 54
    Interesting, noticed when the summer formulation, aka, more ethanol came out mileage dropped a little. But this weeks tank is 22.0 on premium. What is your total miles, mine is at 5600.

    Deep in the heart of Texas,

    Go Cowboys,

    Cheers,
    Gary
  • gxpjoeypgxpjoeyp Member Posts: 38
    WELL THE COWBOYS @#$%^^&& HA HA HA 1ST AND FOREMOST, AND I GOT 4300 MILES ON MY 06
  • ocmike3ocmike3 Member Posts: 232
    I've only got about 4400 miles on my 2005 GXP. My last road trip was cruising 65mph +/- a couple mph and the 5.3L DOD returned 27.6mpg (232 miles @ 8.4 gallons premium) running the A/C for a good portion of the trip.
    I know during the winter months we have to run 10% ethanol and my mileage drops by 10 -15%.
    I do know if I let my foot control the throttle the mileage isn't nearly as good. ;)
  • rmozolrmozol Member Posts: 124
    I finally got an out of town trip, to check mileage. I filled in the city and headed out. For a 123 mile trip one-way, I got a measured 26.1, with 27.0 DIC. This included a couple of traffic jams, with stop and go. I used the cruise between 70 - 72. I was in a wedding procession with some 69 - 70 GTO Judges, so hit it a few times and did some burners! It dropped to 20 something (DIC) after this city driving and gas useage. Others heard this thing coming down the street too. I thought it was just loud from behind, but I guess not! On the way home, I got a measured 26.5, with 27.8 DIC. I used premium, and a light throttle to get up to speed. I only have 2436 miles on it too. I'm content with this mileage.
  • blckthreeblckthree Member Posts: 153
    I sure don't know how you got 26/27 on the highway, wish I could. Only time I came close to that was one day on some flat highway with a tail wind, got 25, never seen it since.

    My average highway speed is about 80mph, give or take a bit. Average mpg is about 21-22. Not bad for 80mph, but not what I had hoped for. I won't complain, it is still a nice ride and cheaper to feed than the old Yukon was.

    Just over 13000 miles now, no troubles except for an OnStar module going out. Didn't bother me, except that it had some message every time you started the car. Got tired of the car talking to me.

    Mike
  • rayainswrayainsw Member Posts: 3,192
    "THE 07 IS 17/25 3 MPG LESS THAN THE 06"

    I have not been to my dealer since 2007s started arriving.
    Was this the sticker on a car - or "Click Here For Window Sticker" on GMBuypower or Pontiac's web site?
    ( These are often wrong. )

    The EPA website shows the 2007 as 18 \ 27 ( 21 combined )

    http://www.fueleconomy.gov/feg/findacar.htm

    And on the Pontiac web site, at the beginning step of "Build Your " - it shows 17 \ 28 for the GXP.
    Odd.....

    - Ray
    With much experience & many thoughts on MPG . . .
    2022 X3 M40i
  • rayainswrayainsw Member Posts: 3,192
    My gas mileage is “fine”.

    Details:

    First – highway MPG: I have achieved over 22 MPG for a full tank only a few times in over 19,000 miles. They were close to ‘ideal’ “real-world” conditions.

    ‘Ideal’ “real-world” conditions - probably sounds like an oxymoron, but what I mean is: In the “real-world”, I am NOT constrained by the EPA test limits on rate of acceleration when I merge or pass or leave a traffic light. In the real world, roads have at least some traffic and I am constrained largely [ on Interstates ] by local speed enforcement rather than EPA test max speed (still 60 MPH!!) and I am free to drive with my A/C on. ‘Ideal’ conditions mean relatively light traffic, cool enough ambient temps to be comfortable without the A/C compressor running, cool enough that the air entering the motor is relatively dense, and mostly running on roads with little significant elevation change. And only me in the car, and no more than a weekend case.

    My overall fuel mileage likely now stands at close to 19.0. But if I remove a few of the ‘best’ tanks ( not typical ) from the equation, the average probably drops closer to 18.5.

    Second, I am satisfied with the overall fuel mileage, given the available performance & how often I utilize it. (Many smiles per gallon, thank you.)

    My “around town” MPG reflects the fact that I really enjoy the V8’s acceleration – feel & sound. And I use it whenever I (safely) can. And I use all of it. WOT. Often. Thus I do not achieve the EPA estimate there. No big surprise.

    [ The GXP’s acceleration is really the one dynamic performance aspect where I feel like I can legally and safely utilize 100% of the available performance = HP & TQ on public roads. Perhaps not for long at any given time, as more than 10 or 15 seconds of WOT, in second gear, will have this car moving faster than any open road speed limit in the US. But compared to lateral acceleration & braking, it is a thrill that I can regularly enjoy, asking it to deliver absolutely all the power that it has to give. In cornering, for example, I always try to leave significant margin for the unexpected & unpredictable – sand or oil or water across an apex, or another driver doing something ill advised. Acceleration is something that I can enjoy - every time I drive my GXP! ]

    Although I have seen (and quoted here) that GM states DoD can function at up to 80 MPH under absolutely ideal conditions, my feeling is that in the real world, the slightest headwind, acceleration to pass, or uphill incline, etc. will result in DoD = off.

    And the point in the fuel mileage vs MPH curve where above a certain MPH, under certain specific conditions, DoD will not engage - likely results in a sharp drop in MPG. In fact, I’d predict that it will result in a discontinuity (??) in the curve. Meaning a straight drop, where DoD disengages, then a continuation of the downward sloping curve – at a substantially lower MPG level as speed continues to rise.

    For example. One might expect a somewhat linear drop in MPG as speed rises across the range of typical US highway travel. (Yes, I know, not really linear and not over all speed ranges, etc)

    But for purposes of illustration here - If I assume that at an absolutely steady speed of 60 MPH, my GXP can achieve 30 MPG, then at 65 it might be capable of 28 and at 70 it might be 26 and at 75 it might be 24 and at 80 it might be 22 and at 85 MPH, 20 MPG.

    If DoD is operable up to 70, but will not engage starting at say 73.14159 MPH for instance, the numbers might then look like this:

    MPH\MPG

    60 – 30 (DoD on)
    65 – 28 (DoD on)
    70 – 26 (DoD on)
    75 – 20 (No DoD - instead of 24)
    80 – 18 (No DoD - instead of 22)

    I am making these numbers up, but I believe they are in the range of possibility \ reality for my GXP.

    This would mean that exceeding the DoD engagement threshold would cost something like an additional 20 or more percent (24 with DoD vs. 20 at 75 MPH without DoD and 22 vs. 18 at 80, etc.) beyond the expected decrease as speed rises beyond whatever that critical speed actually is. My driving suggests that the threshold speed ( above this, DoD does not engage in ** my ** typical driving ) is between 70 and 75.

    But that’s just me speculating.

    YMMV.

    - Ray
    Still enjoying the drive – and not obsessing about MPG . . (?)
    2022 X3 M40i
  • ocmike3ocmike3 Member Posts: 232
    I think the key is being able to set the cruise and let it go... I do know when I run 75-85mph I notice that the DOD doesn't kick in nearly as often as 65-75mph. I know on a couple of tanks where it was mixed city with on-off freeway romps, my GXP was lucky to get 18mpg.
  • chats1chats1 Member Posts: 158
    Hi! I have 15,500 miles on my 2006 GXP which I purchased last August. Car has run great and I have gotten up to 28.7 on it. Mostly highway driving. Used it alot in August going down to the Jersey Shore and the mileage was great. Can't complain at all. Chats1
  • wufidowufido Member Posts: 3
    I need desperate help!!! 12.2MPG (yea some people think they got it bad with (20MPG) It was at 11.0 MPG before everything I'ved replaced, heres the list.
    1.Rebuilt SuperCharger
    2.ACDelco SparkPlugs
    3.Wire Set (spark plug)
    4.oil change every 3K (oil filter too)
    5.New PCV Valve
    6.New O2 sensor (before catylic)
    7.New Fuel Filter
    8.K&N filter and intake

    Anyone out that can really help. with any Idea Please EMAIL ME at Sol9586@yahoo.com as you can see there has been alot of money invested and im not seeing any progress. 12.2mpg city / and 12.5mpg hwy. HELP!!! HELP!!! HELP!!!
  • wufidowufido Member Posts: 3
    well i've read that the GTP has an 18gal. tank. I reset the gallons used every time, but when I use it and the needle get down to like an 1/8th. it says i'ved only used 12-13 gallons. I reset the tripometer and from a full full tank I get 180-200 miles and the needle is low again like an 1/8th. does it sound weird or wat....
  • swimmerman272swimmerman272 Member Posts: 2
    We have a 99 GTP that gets (according to the calculator built in) an avg of 21 mph (probably 80% city driving so far.) Then again, I can get it down to about 14 if I get on the supercharger...
  • bobthebikebobthebike Member Posts: 11
    Just turned 104K and I rarely get under 28mpg w/ highs up to 31mpg. Fantastic drivetrain and looking forward to 200K!
  • bond007mgmbond007mgm Member Posts: 4
    My 1999 Grand Prix GT only gets about 19 to 20 MPG with regular driving on highway and city. I heard this is normal. On my trip though on the highway only I was averaging 25 MPG.
  • mygxpmygxp Member Posts: 2
    it's called wind resistance. anything over 60/65 you are just pissing your gass money away
  • gearrgearr Member Posts: 21
    I have a 06 GT 3800 supercharge and I drive a lot of back roads
    and I am getting 25 to 28 a GAL.
    Gearr :)
  • cnwcnw Member Posts: 105
    I've got a 2007 GP GT, 7000 miles. When it was "brand new, fresh from dealer" and less than 2000 miles, we had one tank of gas--Albuquerque to Farmington--that we got 32+, hand calculated--not DIC readout. Average speed was 65 mph. We continue to get excellent mileage when out on open roads.
  • wikiwiki Member Posts: 3
    I've noticed the weirdest thing. I've had my 2007 GP for 6 mos now and drive ~ 42 mi total to and from work everyday (30hwy/70city) and was getting about 20.8 mpg (hand calculated) and I recently did my oil change and also bought a mountain bike. Since I live in an apartment, it's not very convenient for me to bring it inside, so I decided to just leave it in the trunk (w/ the back seat down, it fits very well, just have to be careful when pulling it out not to scratch the paint or damage any of the inside trunk wiring). Ever since I've had the bike in the trunk, my mileage is about 23 mpg same driving patterns, weird, isn't it? We're told that to help fuel economy we're supposed to remove any unecessary loads from the car, but in this case what gives? If anybody has an explanation for this, please let me know. It's not a rwd, so the added weight on the rear wheels is just an added dead weight (imho) I'd think. Or maybe it just evens the weight between the front and rear wheels and that makes it easier on the powertrain?
  • tonypeachestonypeaches Member Posts: 1
    I just bought a 2002 Pontiac Grand Prix GT and I'm a little concerned with the gas mileage. When I bought the car, the average mpg gallon displayed was at 20.8, a pretty low number but something I was willing to deal with. I wanted to see for myself the gas mileage I was getting so I reset it. After about 100 miles of driving the average was around 15 or 16 mpg. Sure most of my miles were city, but i dont think it should be that low. I had a problem with the car a week after i bought it. when i accelerated the car would somewhat pop and jerk and would stop accelerating for that split second. I brought it to the shop and they claimed they couldnt find anything wrong with it. So I continued driving it. I reset my mpg meter again and over the next week i averaged 19.4 mpg.Then the SES light came on. I brought it to the shop, they scanned it and a code showing a problem with the MAF sensor came up. They cleaned it out, saying it was clogged, and gave the car back to me. The mechanic also said that the clogged MAF sensor could have been causing the previous problem I had. Now that I have the car back, I am averaging 15 mpg. wtf is up?
  • jeves715jeves715 Member Posts: 6
    Don't feel bad! I have a 2000 prix, just changed the MAF sensor and still getting [non-permissible content removed] gas mpg. The check engine light went out, but no improvement on gas. If you find something out let me know.
  • jeves715jeves715 Member Posts: 6
    2000 Grand Prix 3.8, I just changed the MAF sensor, check engine light went off, it also seems to run better but no change in MPG. If anyone can tell me what to do that would be great. Thanks! Jason
  • rmorriosnrmorriosn Member Posts: 1
    I get 12 mpg and cant find out a fix.i have done a lot of this and that and still no improvement.need a fix
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