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Sedans Pontiac Grand Prix Pontiac Grand Prix: Real World MPG
71 messages, Last post on Jul 03, 2008 at 6:54 PM
You are in the Pontiac Grand Prix Forum. Your Hosts are pat & karens
| 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. | |
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Replying to: gxpjoeyp (Aug 17, 2006 3:09 pm) 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 . . . |
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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 . . (?) |
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Replying to: blckthree (Aug 21, 2006 10:04 am) |
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Replying to: gxpjoeyp (Aug 17, 2006 3:09 pm) |
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Nice to hear about the 26-27 mpg ocmike. I'll see if I can top that  I'm getting really jazzed...still waiting for my gxp to be delivered. Should be any day now. By the way, Gxp Mpg sounds like a good Serbian name, or a heckuva Scrabble word.
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Replying to: splatsterhound (Mar 24, 2006 12:52 pm) You will love it when you get it. PS one BMW guy and and two Maxima's just stared in the parking lot. PPS: My sun clip on my prescription glasses, filters out the light frequency of the HUD. Anybody else have this one? With too big of grin, Bubbaman 
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Replying to: bubbaman999 (Mar 24, 2006 1:59 pm) Base radio -- I'm adding upgraded speakers. Side airbags...but NO SUNROOF! I can't stand the things cuz I'm always hitting my heads on them, on just about any make or model.
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Replying to: splatsterhound (Mar 24, 2006 5:05 pm) Cheers, Bubbaman |
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Replying to: bubbaman999 (Mar 24, 2006 1:59 pm) No problems though! 
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