god awful fuel economy grand prix gxp
06-12-2009, 02:44 PM
#21
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What's with all the bad mileage? I enjoy driving my GXP (front tires have less than 2/32 tread after 16.8k miles) and I've never avg less than 18mpg. My hwy is 28-30mpg. My normal mix driving is 20-21mpg and that includes some mountain driving and lots of curves.
You don't see too many straight flat roads in Western Oregon.
You don't see too many straight flat roads in Western Oregon.
06-12-2009, 04:54 PM
#23
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It is totally dependent on how I drive. Keep it at 55 and I flirt with the upper 30's. 75 and I am down in the lower 20's. 70 will net me in the mid-upper 20's. (all per DIC, so while perhaps not accurate, still good as a comparison).
06-12-2009, 05:57 PM
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Last edited by Heslekrants; 06-12-2009 at 06:07 PM.
06-15-2009, 05:57 AM
#25
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Just returned froma 900 mile drive to the Outer Banks, NC and I averaged 28.5 mpg for the trip back and 28.9 for the trip down going 65 to 70 the whole way. No tune either. I also know for a fact that my car is running rich and I still get around 17 to 18 mpg city driving. I can't wait to see what I get once it's tuned correctly because my car was running so rich that it threw a code at one point. Not sure what's up with these bad numbers. I know the Impy's are around what? 200-400 lbs heavier than the gp's. Another possibility is the god aweful RS-A tires compared to the Bridgestone Potenzas, or in my case the F-1 all-seasons, crappy tires have more rolling resistance and can cause worse gas mileage, I got almost 2 mpgs better on my cobalt when I switch my cobalt to Michelin MXM4's from continentals! All this crap rolled into one could have something to do with it. From what I've heard, the 05's had PCM problems that when you upgrade the air intake it causes the causes the PCM to run in a rich state until you get it tuned, which is my problem, dunno if that has anything to do with the Impys or Montes though.
06-15-2009, 12:23 PM
#26
I took did a 250 mile trip this weekend. Temps in the moring were high 70's. on the way home 55-60 degrees. On the way back i was fighting wind. I did 80mph about 90% of the time. A/C on and everything. On the way up my DIC was reporting 25MPG.. Then on the way back with the wind it Dropped to 23MPG. When i filled up i had a 22.9MPG.. Over all i found if i reset my DIC avg MPG when i fill up the readings are close to real life. So I believe i was actually getting 25MPG running 80mph. If so that was awsome.
06-16-2009, 04:42 PM
#28
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Wow..My 07 Tahoe 4x4 with 320 HP 5.3 and DoD gets about 15.5 MPG in town, so under 15 in a passneger car is pretty bad.
We've had our 06 Impala SS about a month now, and we get about 25 MPG on a given tank. Of course, our commute is 94 miles each way, with a combo of mountain roads and open highway. We do go up and down the I5 Grapevine everday, with the downhill leg mileage being around 30 MPG, and the uphill 21. This is at 65 MPH.
One item of note is not to trust the DIC mileage. Our DIC is actually pessimistic. It will read our 23.8 for a tank, when it's actually 25 MPG doing the math.
I love the car, though!
We've had our 06 Impala SS about a month now, and we get about 25 MPG on a given tank. Of course, our commute is 94 miles each way, with a combo of mountain roads and open highway. We do go up and down the I5 Grapevine everday, with the downhill leg mileage being around 30 MPG, and the uphill 21. This is at 65 MPH.
One item of note is not to trust the DIC mileage. Our DIC is actually pessimistic. It will read our 23.8 for a tank, when it's actually 25 MPG doing the math.
I love the car, though!
06-16-2009, 06:29 PM
#29
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I think the important thing to keep in mind is that everyone's "city" driving conditions can be drastically different. city driving in some middle of nowhere place means having a stop sign or traffic light every once in a while. city driving for someone else might mean driving through Midtown Manhattan.
06-16-2009, 10:33 PM
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I average 20-21 in mixed. Hard not to offend but my bet is it's your right foot. I don't granny it but I don't dog it either. My best average is over 21 but it's not all city, then I drop to about 19-20. City as in Detroit, crap drivers, stop go. Also, I always use tap shift so can't blame or thank that.
06-18-2009, 10:27 AM
#31
Heavy? 3600 pounds is not that bad for how big the car is... G8 weighs 4100 pounds, the new Taurus SHO weighs 4400....
I get 17.? according to the DIC with mostly city. 8 miles each way on my commute. 93 octane with no mods other than K&N intake and no resonator.
Yeah, I wish it was better, but I am not bitching because as we stated the car runs in V8 mode in the city and idling so that is where my MPGs drop. On the highway I am really happy with the mileage.
What I think we need is a 5 or 6 speed transmission considering you can't get into 4th until 50 mph (more or less).
I get 17.? according to the DIC with mostly city. 8 miles each way on my commute. 93 octane with no mods other than K&N intake and no resonator.
Yeah, I wish it was better, but I am not bitching because as we stated the car runs in V8 mode in the city and idling so that is where my MPGs drop. On the highway I am really happy with the mileage.
What I think we need is a 5 or 6 speed transmission considering you can't get into 4th until 50 mph (more or less).
06-18-2009, 10:36 AM
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Yes, they are heavy for being such a small car. They may not be as bloated as some others, but they are loaded up with options and heavy for the space you get inside them.
06-18-2009, 10:50 AM
#33
It's a full size car? Longer and wider than both the SUVs in the family and most cars I park by so I don't really understand the "small car"? EPA classifies it as a "Mid-Size" which is an interior size of 110-119.9. After checking around the internet the average mid size weights in at 3500... So I still don't see how its a heavy small car?
06-18-2009, 11:20 AM
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It's a full size car? Longer and wider than both the SUVs in the family and most cars I park by so I don't really understand the "small car"? EPA classifies it as a "Mid-Size" which is an interior size of 110-119.9. After checking around the internet the average mid size weights in at 3500... So I still don't see how its a heavy small car?
Still not sure why you call it a full size and then talk about it being a mid-size classification, but it is definitely heavier than it should be for it's dimensions. Your assertion that internet searches claim an average weight of less than the LS4 cars (with aluminum blocks on our side to help with overall weight) reinforces the idea that they are built heavier than other similar sized cars. Hope that clears up your confusion!
06-18-2009, 11:44 AM
#36
Excuse me use of full size car, I started the post out and didn't go back to update that part after I looked up the EPA classification.
Yes it is heavier than the AVERAGE mid size but its only about 100 pounds heavy. Which really isn't terrible at all. Considering cars nowadays, see examples form before, are treading into truck and SUV territory at > 4000 lbs... Plus all the extra creature comforts that are provided that the AVERAGE mid size doesn't have. That includes a V8 motor with most midsize cars don't have.
Yes it is heavier than the AVERAGE mid size but its only about 100 pounds heavy. Which really isn't terrible at all. Considering cars nowadays, see examples form before, are treading into truck and SUV territory at > 4000 lbs... Plus all the extra creature comforts that are provided that the AVERAGE mid size doesn't have. That includes a V8 motor with most midsize cars don't have.
06-18-2009, 08:30 PM
#38
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I believe the trick to gas mileage in these things is learning how to drive them for gas mileage. I've found the best way to get good mileage out of them is to get them up to speed quickly and then cruise. Mine averages 21.8, mostly highway but some stop and go there as well. I starter driving my 08 like any other car (slowly accelerating up to speed and then cruise) trying to get good mileage out of it, and wasn't having any success. Tried the harder acceleration and getting to cruise faster and started to get good numbers. Makes sence by getting it into DOD faster.
Cheers
BigRat
Cheers
BigRat
06-18-2009, 09:25 PM
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Since putting in the throttle spacer I am getting about 1-2 MPG better and have been averaging over the last 4 tanks about 24 MPG. I drive about 60% highway to work. If I run much more than 75 the MPG starts to drop quickly.
