Consumer Reports: GM's MPG Discrepancy May Affect Older SUVs

CARS.COM — GM’s recent mileage misstatements on its 2016 Chevrolet Traverse, 2016 Buick Enclave and 2016 GMC Acadia could extend to previous model years, according to Consumer Reports.

Related: GM Halts Sales of Three-Row SUVs Over Mileage Discrepancy

GM issued a stop-sale action last week on its three SUVs because the fuel-economy ratings were overstated by 1 to 2 mpg. The Traverse, Acadia and Enclave SUVs on dealer lots will receive new Monroney stickers with the corrected mileage ratings, GM spokesman Tom Wilkinson told Cars.com. The new mileage ratings for the SUVs’ 3.6-liter V-6 engine are 15/22/18 mpg city/highway/combined for front-wheel drive and 15/22/17 mpg for all-wheel drive.

Consumer Reports compared the affected SUVs’ test data to the EPA’s fuel economy numbers and noted that previous model years for the Enclave, Traverse and Acadia as well as the discontinued Saturn Outlook may have had incorrect fuel-economy estimates too. For instance, the EPA lists the 2013-15 Traverse with all-wheel drive as getting 16/23/19 mpg, but the 2016 Traverse with all-wheel drive has been adjusted downward to 15/22/17 mpg.

The SUVs did not receive any significant updates for 2016 that should affect fuel economy. Consumer Reports notes in its test of the 2009 Chevrolet Traverse, it achieved 16 mpg overall versus the Traverse’s EPA-rated 19 mpg combined. However, in 2014, Cars.com essentially matched the Traverse’s EPA combined rating in a 180-mile drive versus other family SUVs.

When Consumer Reports asked GM whether the fuel economy misstatement affects other model years, a spokesman said the automaker “has checked and found no other models or model years were affected.”

An EPA spokesperson told Cars.com the agency was looking into the matter. Spokespeople for GM did not immediately respond to emails and phone calls from Cars.com.

For more on this story, go to ConsumerReports.org.