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GMC Acadia Real World MPG

63 messages,  Last post on Nov 23, 2009 at 8:41 AM

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What is this discussion about? GMC Acadia, Fuel System, SUV


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#54 of 63
Acadia mpg. by olds4
Jul 07, 2008 (6:23 pm)
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My wife and i have a 2007 Acadia which we have enjoyed for well over a year now.I have been very impressed with the mpg of our Acadia = 19-21 city/hwy driving.I truely find it an accomplishment for a vehicle of this size and weight not to mention the amount of power the engine puts out to get this kind of fuel milage.Just to put things into perspective - i also have a 1997 GMC Sonoma,single cab,step side with a 4cyl standard which only gets 24-28 mpg. I just wish my wife could drive a standard so we could trade off sometimes.
 
  I have read a lot of post about Acadias on this site and i have come to the conclusion that most people do not know how to figure their fuel milage.Take my wife for instance - she always goes by what the onboard display tells her,which is sometimes not fully accurite.The onboard display was showing around 17mpg,but when i did the real math my self (miles divided by gallons of gas) it came out to 19mpg.This test being in a 3-day period of driving back and fourth to work-city/hyw 50/50.There are a lot of red lights and my foot is very heavy - so i was very happy with my results.So my point being - if you do not like the mpg that the onboard display shows - just do the math yourself,it may make you feel better.
 
going on 20,000 miles-and my 2nd power steering pump.a happy customer so-far.
#55 of 63
Improvements on MPG by stdavis
Jul 08, 2008 (4:14 am)
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After taking my Acadia back to the dealer and having them go through the car to ensure everything is 100% they told me that a couple of things might help the MPG, so I thought I would pass it along.
First, I took them up on replacing the air in my tires with nitrogen. I thought this was a gimmick, but it was only 39.95 plus tax and I am willing to try anything at this point to improve the MPG. They also told me to run the tiers at 38 psi from the 32-34 I was running. Initially it looks like I gained a 1-2 MPG
Second, they told me to make sure I filled up at Tier 1 gas stations and be sure to only fill up with pure gas, no ethanol. This seems to have given me another 1-2 MPG improvement.
Third, they tell me that GMC will come out with a new spec for their transmission soon and that I could expect a little improvement from this as well, but it might be a while. Apparently, this will only be a programing change in the transmission shift points that should result in fewer shifts between 20-30 mph. I think the transmission shifts fine, but they tell me there are a lot of complaints regarding how much shifting the vehicle does in this range.
The end result for now is that I have seen a change from ~12.5 mpg in town 14.5-15mpg. This is 100% in town driving under pretty much the worse conditions for mpg, with continuous stop and go averaging about 25-40 miles a day calculated manually over several tanks of gas and the on board computer is dead on.
We'll take a nice long road trip soon and see it we can achieve anywhere near the 20mpg+ that so many people have reported getting.
 
I must also say that since our Acadia is only 6 months old and we have put about 6k on her that the dealer told us they would be willing to swap for a different Acadia if it came down to that. I would hate to put this to the test, but at least it was a offer that goes above and beyond what I thought they would do. I told them I might consider giving up the AWD for better MPG if I could get everything else the same. Of course the AWD shouldn't be a factor since all the driving has been done under dry conditions where the AWD shouldn't be kicking in.
 
White Diamond Tri-Coat
08 Acadia SLT 2 AWD
#56 of 63
Re: MPG [chezky] by shoshy5
Aug 07, 2008 (4:17 pm)
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Replying to: chezky (Dec 25, 2007 2:19 am)

we only get 8.2 miles per gallon city NORMAL driving. my armada got b/w 10-11 mpg. just got it about a month ago have to fill it up every 5-6 days and summmer were hardly driving like the schoolyear . the dealer said maybe the computer needs to be adjusted, is the computer eating my gas? also when i accelerate the car kind of kicks like its trying to catch up to speed.
#57 of 63
MPG by txbricklayer
Dec 29, 2008 (8:19 am)
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Drove to San Antonio and back from Houston over Christmas. 2008 Acadia had 22mpg going to SA and 28 coming back. Wind power rules!
#58 of 63
Re: Gas mileage experiance? [lukesdaddy] by acadiaregret
Aug 03, 2009 (10:49 am)
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Replying to: lukesdaddy (May 12, 2007 4:47 am)

I have an 08 AWD Acadia and I get 10 mpg city / 14 mpg hwy
#59 of 63
Re: Gas mileage experiance? [acadiaregret] by stdavis
Aug 03, 2009 (12:01 pm)
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Replying to: acadiaregret (Aug 03, 2009 10:49 am)

If you find any solutions let me know GMC sure doesn't have any. We have never achieved anything better the 12.5-13.5 in town with very little mix of highway and 17-19 on the road. Makes me regret trading the 99 Tahoe that did better and had much more horse power and performance. At least I knew I was giving up fuel economy for performace with the Acadia I get neither.
All GMC could offer was keeping the Nitogen pressure (which is a joke as far as I can tell) in the tires at 38-40 and using 100% gas with no ethanol. I think this results in about 1 mile per gallon difference.
There where rumurs that GMC would come out with a better automatic shifting algorithm for the transmission, but I have never seen it.
#60 of 63
My experience by loach
Aug 03, 2009 (1:23 pm)
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Now that my '08 AWD Acadia is broken in, we've been getting mostly 13-14 MPG city and 20-24 MPG highway depending on conditions. We've never come close to getting the 16 MPG city EPA rating, but easily beat the 22 MPG highway rating if the conditions are favorable.
 
I consider these numbers to be well within reasonable tolerances. The Acadia is a bit of a pig in stop and go traffic, but really shines on the highway for a vehicle this size.
#61 of 63
MPG Explained - 2010 Acadia SLE AWD by victorg009
Nov 16, 2009 (2:00 pm)
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Acadia can archive 30-35 MPG under certain conditions, but in everyday city driving it gets 10-15 MPG only. In 1st week of owning I found it has 2 driving modes: power and efficiency. Efficiency is activated only when cruse control is ON or at higher speed, otherwise it is in hungry power mode with loud engine noise despite standard acoustic package and feels like driving a truck (but after a week of driving you stop noticing noise).
 
When cruse control is engaged, the speed is considered to be constant, and in theory it does not require much power/torque to fight wind/tires drag. Therefore in cruse control the transmission algorithm uses higher gear and lower engine RPM 1400-1600 (2000RPM at 65mph). On the flat road ODBII scanner shows instant MPG 35+ at 40mph, 30MPG at 65mph and slightly less at higher speed.
 
It takes lots of gas to accelerate 3 tons on metal, plastic and rubber, or drive it uphill. Therefore during acceleration/uphill MPG is never above 10, and can be even lower. The only way to increase fuel efficiency for acceleration/uphill is to change driving habits. Buy PLX Kiwi OBDII Scanner and Fuel Saving Device. As for me Acadia proved that I need PLX Kiwi and I will be getting one.
 
Now to the root of low fuel efficiency problem. When not using cruse control at low speed 25-40 mph, transmission algorithm uses lower gear to run engine at 2000 RPM or slightly higher, and car gets about 15 MPG. Engine noise gets louder too. On cruise control on the same road it runs engine at 1400-1500RPM, and about 25 MPG. Efficient lower RPM program handles constant speed even with some uphill/downhill without any problems (ODBII scanner shows good MPG drop when going uphill on cruise control).
 
My 2005 Camry drives at reasonable 1200-1500RPM at lower speeds on flat road, and I believe that Acadia engine can still provide enough power at 1500RPM. I am going to dealer to have transmission reprogrammed to shift to higher gear sooner to match driving with cruise control ON.
#62 of 63
Re: MPG Explained - 2010 Acadia SLE AWD [victorg009] by chrisgg
Nov 22, 2009 (7:41 pm)
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Replying to: victorg009 (Nov 16, 2009 2:00 pm)

victorg009,
Any update on your PLX Kiwi or asking dealer to reprogram transmission to shift to higher gear sooner?
Which model PLX Kiwi are you getting?
Thx
#63 of 63
Re: MPG Explained - 2010 Acadia SLE AWD [chrisgg] by victorg009
Nov 23, 2009 (8:41 am)
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Replying to: chrisgg (Nov 22, 2009 7:41 pm)

Look for "PLX Kiwi OBDII Scanner and Fuel Saving Device" on Amazon. I already have ScanGauge II and it gives me instant MPG on Acadia, and can show summary for all day trips including miles driven, gas burned, average MPG etc, but it requires pressing several buttons at the end of the trip which I always forget, and PLX Kiwi does it automatically. If I did not have ScanGauge II I would get Kiwi already, now I am still scrambling money to get it.
 
My Acadia went through first tank of gas which lasted less than 300 miles, and this includes some highway driving. I am still learning at which speeds (in range 25-50 mph which are typical city driving speeds) transmission shift into higher gear, it appears that at certain speeds it up-shifts and at some others like 25mph stays in 2000RPM range with loud engine noise and 15 instant MPG (25 MPG when up-shifts).
 
Sales department at dealer said I need to talk to service department manager about transmission programming, but I am still building my case which would include speeds at which it stays at silly 2000RPM and how much extra gas in $$$ it burns.
 
However I verified that my statement about cruse control is true – it always shifts into higher gear to stay in 1500RPM range regardless of speed (in city driving), and MPG is 50% higher with lower RPM.

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