Changes To EPA Fuel Economy Testing Procedures Could Impact General Motors

The United States Environmental Protection Agency (EPA) recently announced that it has revised procedures for a critical component of automotive fuel economy testing that will likely impact the fuel economy ratings of future General Motors vehicles.

The updates cover the way in which automakers should calculate road load values in coast down tests, which measure the rolling resistance and aerodynamic drag of vehicles as they glide from 70 mph to a stop on a straight, flat track. The values from these tests are then used to calculate overall fuel economy ratings using the EPA’s test cycle.

“It will be more accurate,” said Chris Grundler, director of the EPA’s Office of Transportation Air Quality, to Automotive News about the revised tests. “Both the EPA and the automakers have a common cause to make sure that customers are getting the best information.”

Some automakers have struggled to apply the tests correctly. For instance, Hyundai and Kia famously agreed to pay a $350 million fine after fuel economy ratings for some of their models were found to be over-exaggerated. Ford also cut the fuel economy figures of some of its vehicles after an internal audit of coast-down data collected from production vehicles revealed errors in road load data in tests involving preproduction models.

Up to this point, General Motors has stayed out of the erroneous fuel economy reporting limelight, arguably having its hands full in handling the ignition switch recall and subsequent recalls. Even so, the EPA’s new guidelines could result in a slight drop in fuel economy across the GM vehicle portfolio going forward.

“I think it’s fair to say that not only are we paying more attention to these processes but the automakers are as well, and that obviously is welcomed,” the EPA’s Grundler added.

In the coming months, the agency will meet with major automakers to discuss fuel economy ratings and testing, as well as ways to improve the accuracy using the new model. In the meantime, we’ll just have to wait and see how the changes will affect GM.