This is a pretty ancient thread, but the only one I can find...
Got my 2008 SLT1 Red Jewel FWD in March (January build), and traded in a 2004 Suburban LT (RWD) for it. Prior to this, I had a 2001 Tahoe LT (RWD)... Anyway, one of the nicer features of the 'Burb was all the stuff you got on the DIC >. There was instant MPG, and 2 average MPGs, one called "Personal" and another called "Business". You could enable the "business" one basically anytime, and I would use the 2 averages for doing multi-day trip things... I would reset the personal one on each fill up and reset the business one at the beginning and end to get an overall.
I always left the DIC showing the instant mpg, since it gave you direct feedback on what your mileage was vs what you were doing with the gas peddle. The one thing that was obvious was that there was no way to get more than 20MPG out of that thing. Even at 40MPH, the instant MPG on the DIC was right at 20, and anything faster would draw it down. I don't understand why the Acadia doesn't have this. I see lots of people posting "reset" the average to see what the instant is... but then you lose the average... and instant "numbers" have to be available to calculate the "instant average"... When my transmission started leaking a few weeks ago, they gave me a 2008 Pontiac G6 with a 3.5 V6, and that thing had instant MPG.
Anyway, I've seen people get their SLE DICs to give them AVG MPG... Since the instant information has to be available, does anyone know if it's possible to get this to show?... other than mashing reset on the AVG?
Oh... city driving to/from work ~15 mile one way commute (moderate to heavy highway traffic) I get 17-19 MPG. Had it on several trips and max I got was 22-23 MPG.
If you don't reset, you have the average for the entire time you've had the vehicle. I'm not sure why that's needed especially as time goes on. Resetting say when you fill up your tank will give you instant mileage as you drive. I do it every time I fill up. If that still doesn't suit your needs, not sure what to tell you.
It would be kinda neat to see instant MPG in the Acadia and I really don't know why this mode was not included. The DIC in my Silverado shows this along with which mode the engine is in, either V-4 or V-8. It's cool to be driving downhill and see the instant mileage pegged at 99 mpg in V-4. ;D I have a couple mile stretch of 55 mph highway on my way to work that is nice and flat where the truck will run in V-4 mode and the instant mileage will be in the mid 20s. Not bad for a 6.0L V-8 with 4.10 gears. Anything faster than 60 mph and it's all V-8 with mileage in the mid teens unless I'm coasting.
The instant mpg is kinda cool. Had it on my '04 Suburban and '01 'Vette. It really can teach you how to drive a bit more economically. I do wish the Acadia had it! If GM could upgrade the software to do it... I'd go for it, even if it cost a couple of bucks.
I always reset the DIC at fill up. I know right after it's reset, it is giving instant MPG, but after a "while" of driving, the "instant" numbers start turning into "average" numbers, since after reset, there is no history, but the history is being built over time.
I usually fill up on the way to work, where I usually jump on the freeway for the commute. By the time I get to work, I've seen as high as 26 (although this is somewhat misleading, since I can usually drive no faster than 45), but by the time I get back home, it's down to 19-20 range. After a couple of more days of local running around it drops some more. If I fill up and reset on the weekend when I'm running around locally, the average will show in the 13-16 range, until Monday... then back up with the steady but slow traffic.
Anyway, the things that are helpful (as other people have mentioned) are exactly what is happening when your accelerating from a stop to the mileage. With instant, you can get feedback on how to improve the mileage. I noticed in the 'Burb that mearly having my foot just gently on the accelerator rather than all the way off had some impact. Also, it's real hard to judge exactly what kind of highway mileage you are getting at different cruise speeds (unless you constantly mash the reset button), or what all the shiftiness in the transmission is doing with cruise on with slight up/down grades on the highway. Honestly, to me (maybe I'm conspiratorial or something), leaving the function off seems to make it harder to get a real guage on if the real highway mileage reported is "really" attainable. The 'Burb was rated 14-18 prior to the EPA derate and 13-17 after. I could tell with the DIC that under "ideal" conditions (speed/wind) that I could get 18 and occasionally a little better. I had thought since the original Acadia said 16-26 that under "ideal" conditions, I could get 26 at highway speeds, but I don't see that. Maybe it's a V8 mongo thing vs a V6 semi-mongo thing or weight or something else.
Anyway, I just wish they would display the information since it has to be available anyway...
Not sure why instant would be that great. It's an average calculation and probably less accurate than an average based on an extended duration. More data points make for better estimations that less (ie instant). The more "instant" the measurement, the more "estimate" (ie extrapolated guess) goes into the displayed number.
This little device, the ScanGauge II, gives you a plenty of numbers and data to look at including instant mpg, coolant temp, battery voltage, air intake temp, and throttle position sensor readings to name just a few, plus it's a scan tool. It plugs directly into the OBD2 port. It's a little pricey, but works very well.