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Greetings all. We purchased new a 2012 GMC SLT FWD Acadia and currently have 56,000 miles. Recent services include 6x spark plugs and coil packs, servicing/cleaning of the K&N Air Filter, oil change and checking the tire pressures (36 psi). Last tank was 12.14 MPG with a running average of 14.2. Window sticker says 17 MPG in town.

By contrast, our 2007 R63 AMG with a 507 HP 6.2L V8, AWD, and 106k miles is averaging 14.4 MPG (last tank at 15.1 MPG).

Clearly something is not correct in the universe here. I will readily acknowledge that my wife is doing the school run and heading to work; total daily driving of ~20-25 miles. What am I missing to ensure that the Acadia‘s 280HP V6 is running correctly!? I’ve checked for codes and found none. It runs on Top Tier fuels (Shell or Sunoco generally, mid-grade).

Any input is appreciated!
 

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Is this MPG something new? Or has it been getting this its entire life?

My Acadia averages between 16 and 17 around town. Most of the time in the lower 16's.

George
 

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Back when I had my '11, my around town average was 14 mpg. I could get 20 on the highway.

I doubt there is actually anything wrong with your '12.....unless you over oiled the silly K&N filter.
 

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My first thoughts are both above. Is the MPG figure new since tune, or always. No idea what I get TBH.
Over oiling on the filter perhaps, or maybe a cracked plug?
How does it run?
 

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Is this MPG something new? Or has it been getting this its entire life?

My Acadia averages between 16 and 17 around town. Most of the time in the lower 16's.

George
It’s been getting progressively lower and lower over the last year. I’d take 16’s happily.

Back when I had my '11, my around town average was 14 mpg. I could get 20 on the highway.

I doubt there is actually anything wrong with your '12.....unless you over oiled the silly K&N filter.
Not my first K&N; it’s correctly done.

My first thoughts are both above. Is the MPG figure new since tune, or always. No idea what I get TBH.
Over oiling on the filter perhaps, or maybe a cracked plug?
How does it run?
Plugs are direct from GM, same as coil packs. It runs well enough; not like the R63 for sure! It’s smooth at idle, pulls cleanly and without hesitation. No misfires felt or based on checking the ECU.
 

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My 2011 SLT2 had equally poor fuel economy. IIRC, early on was able to squeeze 22 mpg out of it on long, flat highway cruises...other than that, it was probably averaging about 15-16 mpg combined city/hwy. With a lot of city driving, I often saw a 13 mpg average.

One of the reasons I went into a Terrain this time.

Tom
 

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I've never realized any benefit from running mid-grade fuel - same thing with premium. Change to regular and see if you notice a difference in fuel economy.
 

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My 2011 SLT2 had equally poor fuel economy. IIRC, early on was able to squeeze 22 mpg out of it on long, flat highway cruises...other than that, it was probably averaging about 15-16 mpg combined city/hwy. With a lot of city driving, I often saw a 13 mpg average.

One of the reasons I went into a Terrain this time.

Tom
New generation gets much better MPG. My '18 averages 20-21 and 30+ on road trips.
 

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If all else is OK...
(have you reset the DIC parameters since your last fill up-- or is this the reading since it was last reset who knows when?)
Im thinking your wife has recirculate on.
Or runs AC all the time.
AC compressor and street driving = lower MPG.
Try backing up in reverse slowly-- and turn on the AC-- youll see how much 'power' the compressor grabs-- you will feel a sudden drag.

But- my wife is the same- just runs AC, goes through drive thrus, picks up kids.
She drive the Traverse- and MPGs drop to 12-14.
I drive it- and it jumps to 16-22- depending on my drive.
 

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The a/c running should not change mpg over 1/2 mpg. Here is Florida Panhandle it has been very hot this year. A/c runs a lot. Really no noticeable change.
 

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Discussion Starter #12
If all else is OK...
(have you reset the DIC parameters since your last fill up-- or is this the reading since it was last reset who knows when?)
Im thinking your wife has recirculate on.
Or runs AC all the time.
AC compressor and street driving = lower MPG.
Try backing up in reverse slowly-- and turn on the AC-- youll see how much 'power' the compressor grabs-- you will feel a sudden drag.

But- my wife is the same- just runs AC, goes through drive thrus, picks up kids.
She drive the Traverse- and MPGs drop to 12-14.
I drive it- and it jumps to 16-22- depending on my drive.
The AC is set to 73 and auto.

The a/c running should not change mpg over 1/2 mpg. Here is Florida Panhandle it has been very hot this year. A/c runs a lot. Really no noticeable change.
Agreed; use of the AC should not cause a 4-5 MPG loss in fuel mileage from the window sticker.

I am curious if this is carbon build up related?? That said I’ve dismissed it as the idle is not rough and the engine pulls cleanly.
 

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What other issues am I missing here?! Spark plugs and coils are new, clean air filter, correctly filled tires....
What about ethanol content of the fuel? Shouldn't run any fuel with ethanol content higher than E10.
 

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What other issues am I missing here?! Spark plugs and coils are new, clean air filter, correctly filled tires....
Based on my experience with my '11, you aren't missing anything. It's a big, heavy vehicle that gets crappy mileage.

Over time and mileage certain parts just don't function like new. O2 sensors build up contaminants and while performing with in spec, don't perform ideally. Cats are a consumable and over time will not perform ideally.

What exactly are your expectations?

From my experience the easiest way to for better MPG out of an Acadia is to swap out the 1st gen for a 2nd gen.
 

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What about ethanol content of the fuel? Shouldn't run any fuel with ethanol content higher than E10.
Good point. OP, what fuel are you using with what ethanol content?
Perhaps as speleos said in an earlier reply, just run on 87 octane per GM, and pick a different gas station for a while and stick to it. If you still get lousy mileage, switch stations and try tracking again after a few tanks.
I checked mine on the way in for the first time since purchase, but it fluctuates as I drive, so it's obviously set to trip mileage as opposed to average (haven't looked into how to change that, to the left of that it shows a graph, but no average number). On my trip in I got 21MPG, 10 mile drive, in the city.
 

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What other issues am I missing here?! Spark plugs and coils are new, clean air filter, correctly filled tires....
Oxygen sensors maybe?
They probably have not set the CEL-- but may be getting lazy.
Clean the MAF sensor?
 

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Oxygen sensors maybe?
They probably have not set the CEL-- but may be getting lazy.
I see this statement over and over again, but find it very difficult to believe. I have owned 5 fuel-injected vehicles and never once experienced a drop in fuel economy caused by "lazy" O2 sensors. In fact, a few of these vehicles were driven close to, or over 200K miles and never had an O2 sensor problem. Any perceived loss in fuel economy was resolved by simply changing the air filter and/or spark plugs and running the occasional fuel injector cleaner through the fuel tank. I drove livery cars with nearly 300K miles on them which had the original O2 sensors and could still get the expected fuel economy. Do what you want about changing O2 sensors. I believe the notion that they get "lazy" is frivolous. There's no engineering documentation (that I can find) to back up the hypothesis. If the engine runs properly, the sensors should never get coated with deposits - they will be burned away.

The same holds true for catalytic converters, BTW. The catalyst in a catalytic converter never "wears out," or gets used up. It just gets coated or clogged by deposits, or melted and eroded away from a poorly running engine.
 
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