GM's Flawed Fuel Economy Numbers Could Affect Millions of Vehicles

gms flawed fuel economy numbers could affect millions of vehicles

The strange case of General Motors’ incorrect fuel economy numbers is getting stranger, if it wasn’t odd enough already.

GM announced late last week that it would reprint EPA labels for its 2016 full-size crossovers after the wrong mileage made its way onto window stickers, but Consumer Reports now says there’s something fishy about that.

The official word was that undisclosed changes made to the 2016 GMC Acadia, Chevrolet Traverse and Buick Enclave required the printing of new mileage figures, which, due to a faulty “data transmission,” overstated mileage by one to two miles per gallon.

The vehicles’ powertrain hadn’t changed between this year and last, leaving many to wonder what changes could have been made that would actually lower fuel economy on a newer vehicle.

As Consumer Reports points out, the revised mileage for the 2016 models is lower than that of previous model years. In the case of an all-wheel-drive Acadia, a corrected EPA label for the 2016 model shows a 2 mpg (combined) drop from 2015.

It also means the older range of vehicles beats new models for fuel economy going all the way back to 2007.

Oddly (or ominously, however you want to look at it), when the publication compared the EPA figures for past models with its own observed fuel economy results, the combined mileage from their tests was 2 to 3 mpg lower than the EPA’s. That places the real-world mileage of the older GM triplets closer to the revised 2016 mileage than what was printed on their window sticker.

When contacted, a GM spokesperson told them that “no other models or model years were affected” by the mileage discrepancies.

The EPA asked GM for all data related to the 2016 mileage discrepancy, but it’s unknown if they requested any data dating to previous model years. Either way, the EPA didn’t respond before the report was published.

About two million of the General’s full-size crossovers left dealer lots since they went on the market. If past fuel economy numbers turn out to be inaccurate, it could mean a hefty amount of gasoline expense compensation for GM, a la the Hyundai/Kia controversy of four years ago.

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  • Ponchoman49 Ponchoman49 on May 18, 2016

    Funny but I don't remember all this fuss being made from CR when the 2008 Prius dropped from a claimed 61 MPG city down to a more realistic 48 from previous years when manufacturers had to adjust ratings for stricter more realistic conditions. Most vehicles lost between 1-3 MPG in the changeover but the Prius dropped by a massive 13 for the city rating and 7 on the highway. Now it's a huge deal that a sticker was mis-printed that was off by 1-2 MPG. 22 highway MPG on the Lambda's was always the rating all along on the Buick Enclave with AWD. 23 was the rating on the Traverse and Acadia also with AWD due to less weight and typically smaller tire sizes. It sounds to me like GM is trying to cover there rear ends by just rating all 3 at the new 15/22 figure in AWD trim which makes sense considering that the latest models have more and more equipment being ordered on them and larger 19 and 20" tire sizes are more frequently being ordered which is proven to reduce MPG some.

    • See 4 previous
    • KixStart KixStart on May 18, 2016

      There was no point singling out the Prius, since the test was optimistic for all cars... if unusually friendly to the Prius. I've owned several Toyotas, including a Prius. On trips, every one of my Toyotas routinely beats its highway number. Other makes I've rented do not do so well. If there's a pattern of deceit at Toyota, I don't see any evidence of it.

  • Lack Thereof Lack Thereof on May 18, 2016

    "The vehicles’ powertrain hadn’t changed between this year and last, leaving many to wonder what changes could have been made that would actually lower fuel economy on a newer vehicle." Well, I dunno, the obvious answer would seem to be reprogrammed shift points, holding gears a few hundred RPM longer and downshifting quicker. With the competition all outclassing them in HP, they have to do something to compete. That seems like something easy to check & verify, because I really don't see any other possibility.

  • Snickel Fritz I just bought a '97 JX 4WD 4AT, and though it's not quite roadworthy yet I am already in awe of it's simplicity and apparent ruggedness. What I am equally in awe of, is the scarcity of not only parts but correct information regarding anything on this platform. I'm going to do my best to get this little donkey back on it's feet, but I wouldn't suggest this as a project vehicle for anyone who doesn't already have several... and a big impressive shop with a full suite of fabrication/machining/welding equipment, and friends with complimentary skillsets, and extra money, and... you get the idea. If you don't, I urge you to read up on the options for replacing anything on these rigs. I didn't read enough before buying, and I have zero of the above suggested prerequisites... so I'm an idiot, don't listen to me. Go buy all of 'em!
  • Bryan Raab Davis I actually did use the P of D trope, but it was only gentle chiding, for I love old British cars of every sort.
  • ScarecrowRepair The 1907 Panic had several causes of increased demand for money:[list][*]The semi-annual shift of money between farms and cities (to buy for planting and selling harvests)[/*][*]Britain and Germany borrowing for their naval arms race[/*][*]San Francisco reconstruction borrowing after the 1906 earthquake and fire[/*][/list]Two things made it worse:[list][*]Idiotic bans on branch banking, which prevented urban, rural, and other state branches from shifting funds to match demands. This same problem made the Great Depression far worse. Canada, which allowed branch banking, had no bank failures; the US had 9000 failures.[/*][*]Idiotic reserve requirements left over from the Civil War which prevented banks from loaning money; they eventually started honoring IOUs illegally and started the recovery.[/*][/list]Been a while since I read up on it, so I may have some of the details wrong. But it was an amazing clusterfart which could have been avoided or at least tamed sooner if states and the feds hadn't been so ham handed.
  • FreedMike Maybe this explains all the “Idiots wrecking exotic cars” YouTube videos.
  • FreedMike Good article! And I salute the author for not using the classic “Lucas - prince of darkness” trope, well earned as it may be. We all know the rap on BL cars, but on the flip side, they’re apparently pretty easy to work on (at least that’s the impression I’ve picked up). On the other hand, check the panel fits on the driver’s and passenger’s doors. Clearly, BL wasn’t much concerned with things like structural integrity when it chopped the roof off a car designed as a coupe.