The US Environmental Protection Agency said today that it will launch sweeping changes to the way it tests for diesel emissions after getting duped by clandestine software in Volkswagen cars for seven years.
In a letter to car manufacturers, the EPA said it will add on-road testing to its regimen, "using driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use, for the purposes of investigating a potential defeat device" similar to the one used by Volkswagen.
The testing would be in addition to the standard emissions test cycles already in place, the EPA said.
VW's sophisticated software allowed its cars to pass tests in the lab and then spew pollution into the atmosphere while on the highway. The changes announced Friday are designed to detect software and other methods automakers might use to rig a test.
The revelations about VW led to unwanted scrutiny for the EPA. Its testing procedures have been criticized for being predictable and outdated, making it relatively easy for VW to cheat using what governmental officials repeatedly describe as a "sophisticated scheme" determined to game the system.
EPA did not initially uncover the problem; researchers at West Virginia University did, using on-road testing that EPA did not.
Chris Grundler, head of the EPA's office of transportation and air quality, defended the agency's testing procedures, noting that passenger vehicles with diesel engines account for far less than 1 percent of overall vehicle emissions of pollutants such as nitrogen dioxide.
"It's not a question of equipment or technology or capability. It's a question of where we deploy those resources," Grundler told reporters.
The EPA has conducted on-road testing on heavy duty trucks, rather than passenger cars, "because that's where the emissions are," he said.
VW has admitted to installing so-called defeat devices on Volkswagen and Audi cars with four-cylinder diesel engines.
The devices switch on pollution controls when they are being tested, but are turned off when the software determines that the cars are back on real roads. The EPA says about 500,000 U.S. Cars including the Jetta, Golf, Beetle, Passat and Audi A3 have the cheating software, and VW says a total of 11 million cars have it worldwide.
