Last post on Mar 20, 2013 at 8:45 AM
You are in the GMC Acadia
What is this discussion about?
GMC Acadia, Fuel System, SUV
#231 of 251 Re: 3800 in the Acadia? [cs350]
Aug 02, 2012 (1:00 pm)
Another alternative is the 3900 V6. I have one in a 2007 Uplander. HP is rated at 240. I have got 27 MPG in 50-55 MPH driving and 23 to 24 MPG on the interstate (70-75 MPH). In either case, the 3800 or 3900 would be a more durable and reliable option in the long run (i.e. 150-200k miles of ownership).
#232 of 251 Re: 3800 in the Acadia? [jpf]
Aug 04, 2012 (8:11 am)
Interesting theories, but we'll never see any of them tested.
If you go back far enough to my earlier posts, my issue is that I am not able to get even CLOSE to the official highway rating of 24mpg.
At 60-65mph, flat roads and no downshifts I have almost made 21mpg, which is the bottom of the "range" of 21 to 29 mpg quoted on the window label. I have no clue how 29mpg could be achieved.
That is the "best ever" number, typical is 19mpg.
I drove GM company cars for 20 years and NEVER failed to meet or exceed the official ratings (and that was under the older more lenient EPA numbers).
I bought the Acadia fully expecting to get better mpg than the vehicle it replaced - a 1995 Buick Roadmaster wagon with a 5.7L V8 that consistently delivered 25mpg on the highway.
THAT is my issue with this car.
#233 of 251 Re: 3800 in the Acadia? [kaydeejay]
Aug 04, 2012 (1:15 pm)
Your mileage with the roadmaster had more to do with the gearing in the 4L60e rather than that pushrod 5.7 v8. That same 5.7 in a '00 Yukon Denali returned 10.5 city and 13 highway.
#234 of 251 Re: 3800 in the Acadia? [obyone]
Aug 04, 2012 (2:58 pm)
So you are saying a 2.93 axle in a Yukon/Denali will get 25mpg??!!
I suspect not.
But you are missing my point.
My Roadmaster was rated at 26mpg under the old ratings (which would be closer to 23 under the 2008 and later standards)
I repeatedly got 25.
My Acadia is rated at 24mpg under the new ratings. I get 19 with a best ever of 21.
THAT is my issue!
#238 of 251 Re: MPG Explained - 2010 Acadia SLE AWD [victorg009]
Oct 07, 2012 (4:26 pm)
I have a 2011 Acadia FWD and became aware the same rpm vs. speed issue as you. At around 40 mph (city driving speed) the engine rpm is 2000. This is very fuel inefficient. When the cruise is engaged, the rpm drops to 1400 which is the transmission shifting from 4th to 5th gear. Similar shifting changes occur at lower speeds as well when the cruise engaged. Of course, I don't normally drive around town with cruise control engaged. Thinking that it should not be necessary to engage cruise to control to have the transmission shift at town speeds, I wrote GM and they sent me to a dealer to have it checked. The dealer hooked up their computer monitor during a test drive and found as I had experienced, that at 40 mph, the engine speed was 2000 rpm and engaging the cruise it dropped to 1400 rpm. Then disenging the cruise the rpm increased to 2000 rpm. Interestingly, we (dealer service tech and service manager) tested a 2012 Acadis. The 2012 shifted as I would hope, 1400 rpm at 40 mph with or without the cruise engaged. Other words GM had corrected the problem with the new models. CORRECTION OF THIS PROBLEM WOULD BE TO SIMPLY RE PROGRAMING OF THE COMPUTER MODULE LIKE THE 2012. However GM tech support would not do this. So all of us with 2011 Acadias and older are stuck with a gas hog. (GM TAC CASE 71-1048356874)
#239 of 251 Re: Gas mileage experiance?_SUCKS [hockessin]
Oct 17, 2012 (8:35 pm)
Poor mileage in city driving is partly the fault of the transmission not shifting from 4th to 5th at speeds around 40mph. The engine thus turns at 2000 rpm instead of 1400 rpm if it would shift. Other cars I have driven have an engine speed around 1200 to 1400rpm at 40mph. If you engage the cruise control it will shift up to 5th at these speeds and if you disengage the cruise it will shift back to 4th. I tested a 2012 and this problem has been corrected. The shifting pattern was verified by the dealer. The problem can be corrected by re programing the computer module. I complained to GM and they refused to do anything. This is a matter of poor engineering and a big company ignoring the customer. So long GM.
#240 of 251 Re: GMC Acadia Poor Gas Mileage - Yelp?! [gmcustsvc]
Oct 22, 2012 (6:07 pm)
To Caron, GM Customer Service, - the problem will not be taken care of until GM TAC let's the dealers re-program the computer module to let the transmission upshift from 4th to 5th during city driving thus reducing the engine rpms from 2000 to 1400. The driver can force the shift by engaging the cruise control, but in city driving that is silly. Engaging the cruise at 45mph will also permit an upshift from 5th to 6th reducing the engine speed to 1200 rpm. Why can't GM get with it and help out Acadia owners get better gas mileage?