The dieselgate scandal has certainly called into question the credibility of reported vehicle emissions, which is why the the United States Environmental Protection Agency (EPA) will significantly expand its on-the-road emissions tests to cover all makes and models of diesel cars sold in the country.

Previously, it was revealed that more than 11 million Volkswagen cars were installed with “defeat devices” that allowed it to detect if it was undergoing testing, whereby emissions controls will be engaged in order to pass these tests.

The EPA’s new testing standards will now include real-world conditions besides the traditional laboratory setting, in order to increase the possibility of catching any significant discrepancies in emissions results compared to those claimed by car manufacturers.

According to the New York Times, the EPA completed its first round of tests under the new methodology on vehicles under the Volkswagen Group brand last week, where it was revealed that 10,000 cars fitted with the Group’s 3.0 litre V6 TDI engines were said to feature the same “defeat devices”. Volkswagen has since refuted the EPA’s claims.


The expansion of the EPA’s testing regimen, which previously only involved road testing for pollutants on large trucks, would also include road-test spot checks on older cars to ensure that their pollution-control mechanisms are still efficient. These tests will be done in cooperation with regulators in Canada and California.

Speaking to the daily, Christopher Grundler, director of the office transportation and air quality at the EPA declined to describe the tests, only stating that the EPA will focus on 2015 and 2016 model year diesel cars. They will also be performed on all new cars that manufacturers seek to certify as well.

“Manufacturers have asked us what the test conditions would be, and we’ve told them that they don’t have a need to know. It will be random,” Grundler said. However, the new testing regime will not entirely replace the laboratory method of testing, instead helping to validate the findings obtained in the lab.