General Motors issued a stop-sale order last week to its dealers of 2016 Buick Enclave, Chevrolet Traverse, and GMC Acadia SUVs, calling for those models not to be sold until a correction could be made to the vehicle's window stickers. The concern is that the stickers overstate fuel economy by 1 to 2 mpg. A GM spokesman told Consumer Reports that the automaker is in the process of updating those figures in advertising materials, marketing, and websites, in addition to the window stickers on about 60,000 crossovers currently on dealer lots.

However, when Consumer Reports looked at our own historical test data next to fuel economy numbers from the Environmental Protection Agency and GM's own claims, it seemed like there might be more to this story. It's possible that the stated figures for the Enclave, Traverse, Acadia, and also the discontinued Saturn Outlook may have been incorrect for years.

For example, the EPA's site fueleconomy.gov shows the combined city/highway fuel economy for the 2015 Acadia AWD at 19 mpg—that’s two mpg better than the revised numbers on the 2016 model. When asked whether the discrepancy extends to earlier models, a GM spokesman responded via email, saying that the company, “...has checked and found no other models or model years were affected.”  

GMC Acadia comparison on fueleconomy.gov
GMC Acadia comparison on fueleconomy.gov

The Enclave, Traverse, and Acadia are essentially triplets—all are built on the same platform and share the same powertrain—and the 2016 models are not significant refreshes. After the company updates the stickers for these 2016 crossover vehicles, the prior models from 2007 to 2015 will now all have better stated fuel economy numbers than the new vehicles in GM’s dealerships. It seems unlikely that the company would change the powertrain on these carryover models so late in their model cycles in a way that would cause a dramatic, negative impact on fuel economy. When asked about this directly, GM declined to give a specific answer regarding any substantial changes to these vehicles.

Consumer Reports has previously tested the real-world fuel economy of three prior models of these GM crossovers and found that they performed below their official EPA numbers (data below). While it’s not unusual for our test findings to vary from the EPA figures, the difference is usually just one or two mpg. In Consumer Reports testing, we saw up to a three mpg difference from the EPA figures.  

Fuel Economy Comparison

Consumer Reports overall mpgEPA overall mpg
2007 Saturn Outlook XR AWD1618
2008 Buick Enclave CXL AWD1518
2009 Chevrolet Traverse LT AWD1619

We reached out to the EPA to see if the agency is investigating this possibility. We had not yet received a response.

If this problem extends to the full breadth of this model generation, it could potentially impact more than 2 million crossovers sold in the U.S. over the past decade.

Using the EPA’s calculator on fueleconomy.gov, we found that a decline from 19 mpg overall to 17 mpg would cost an average consumer about $200 per year. Compensating owners for not delivering the expected fuel economy could be quite expensive.  

Hyundai found itself in a similar situation in 2012 when an EPA spot check discovered that some 2012 and 2013 Hyundai and Kia models made exaggerated mpg claims. The automaker issued debit cards to customers to pay for the estimated additional fuel costs based on the actual miles driven, plus 15 percent. 

In GM’s case, given the time in service of many of these vehicles, a misstatement of fuel economy could have cost many customers $1,000 or more by now. Consumer Reports will continue to follow this story as it develops.