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Sedans Pontiac G8 2008 Pontiac G8
1265 messages, Last post on Jul 21, 2009 at 10:14 AM
You are in the Pontiac G8 Forum. Your Hosts are pat & karens
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Replying to: rayainsw (Nov 26, 2008 9:57 am) Along with mpg, I'd appreciate your thoughts on the seating position. I'm 6'3" and head and shoulder room are important to me. Gene
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Replying to: etcarroll (Dec 03, 2008 11:07 am) And the sunroof isn't a problem, either. Dan |
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I took my first trip in the new G8 GT “ex-urban” = outside the Atlanta metro area last weekend. I drove a total of over 700 miles. My drive, each way ( Duluth, GA to the Fla. Panhandle ) is almost exactly 350 miles each way. One ‘leg’ = 3 hours is approx. 200 miles of interstate, with limits varying from 55 in a few construction zones to 70 MPH. The other leg is approx. 150 miles, also 3 hours, because it is primarily speed limited to no more than 55 MPH, and includes a significant amount of 2 lane, through small towns & around Tallahassee - with even lower limits. The V8 is still quite ‘green’. In 2 fills ( the first = approx. one half tank and second = approx. three quarters ) each averaged between 22 and 23 MPG, calculated by Excel. [ I had reset the MPG several times, so no verification of DIC display accuracy, yet. ] I did run some errands around where my friends live, and even ran 12 or 15 miles or so in & around Tate’s Hell – on fairly smooth but dirt roads, at 15 to 25 MPH, but otherwise, these were ‘easy’ miles & relatively good conditions, from a fuel economy standpoint. At one level, I find these results somewhat disappointing. As I have written here, I expected that AFM \ DoD would allow 'real world' cruising MPG to meet or exceed the EPA number of 24. This trip, I was in no great hurry & did not cruise at much above “2 or 3 MPH over the limit”. I tried no ‘hypermiling tricks’, but drove conservatively. The temp was moderate and A/C was off for most of the time. I kept the gear lever in “S” – not “M” to insure that AFM would engage whenever appropriate. I utilized WOT ( or nearly ) only a few times during each tank’s run – typically to merge onto Interstates. Over half the driving is over fairly level terrain. I used cruise control wherever safe. I was expecting higher numbers. I have driven the exact same route about a dozen times, and this is the fifth car I have driven to my friends’ house. I had expected 25. 22.5 does not thrill me. My Corvette returned just over 28 under near identical conditions – even when nearly new. Tests at steady cruise on straight, level deserted roads: Cruise set at 60\61 = 25-26 MPG. Cruise set at 62\63 = 26-27 MPG. Cruise set at 65\66 = 25-26 MPG. Again, A/C = off, Cruise = on, and enough DIC display cycles to verify reasonable accuracy. . . These are all I had time for, before traffic intruded. That’s all I know. I will add, as I have posted here before, that I certainly did NOT select the G8 GT expecting the same MPG as my Corvette. I did expect to meet or exceed the EPA number, under conditions like these. And, with premium gasoline currently near $2.00 / gallon, an additional 2 or 3 MPG would only save me something like $5.00/week – driving 15,000 miles per year. Not enough to trouble me much . . . - Ray Still hoping for an improvement as break-in proceeds . . .
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Ray, How many miles were on the G8. You say the AC was off, but were the windows open?
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Replying to: mrpushrod (Dec 03, 2008 12:25 pm)  start of trip: 234 miles. Sunroof open "full vent", other windows closed. Seats = I found them very comfortable & supportive... - Ray Another tank fill scheduled for tomorrow AM... |
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Replying to: rayainsw (Dec 03, 2008 12:00 pm) Does your gas contain ethanol? The gas mileage of my three cars drops from 7% to 10% when using E10. Modern engines are optimized for gasoline. It's hard to tell, but I suspect E10 interferes with the cylinder shutoff in my 300C on interstate highways. |
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Replying to: pafromfl (Dec 03, 2008 6:26 pm) |
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Replying to: pafromfl (Dec 03, 2008 6:26 pm) No.
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Two more data points, for those playing along at home: Point 1: I filled the tank early this AM. Traveled 296 miles since filled. Gage showed just under a quarter tank remaining. “RANGE” showed 87 miles. Fill took 14.0 gallons of premium – at $1.86.9/gal. That is 21.1 MPG. DIC showed 21.7 MPG. Approx two thirds of this tank was a portion of the Interstate leg driving home from my Florida trip = 65 to 73 MPH. The other third was my usual commute, in & out of MidTown Atlanta. Point 2: As soon as I filled the tank, I drove my typical inbound commute. Warm engine, A/C off. This is approx 18+ miles of Interstate, starting at approx 5:45AM – so reasonable traffic – no cruise control – speeds generally 60 to 75 MPH. When I left the Interstate, for the final 3 miles or so of surface street driving, the DIC showed 22.4 MPG. Driven identically, under the same conditions, my Corvette’s DIC would show 28 to 29 MPG. Car: 2009 G8 GT – just passed 1,000 miles. - Ray Hoping for some improvement, once she is broken-in . . . |
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Replying to: rayainsw (Dec 04, 2008 3:37 am) is there a specific-gravity test like the little turkey-baster with tiny floating balls inside for testing car batteries? i understand that all "gasoline" in USA has a nonzero and nontrivial amount of ethanol, but i'd prefer to be wrong about that.
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