Following the Transport and Environment 's study that ﻿we reported last week , which claimed that 80 % of new diesel cars exceed EU pollution limits as manufacturers had been making alterations to cars in order to pass emissions tests ; the Environmental Protection Agency ( EPA ) has accused Volkswagen ( VW ) of installing software on cars sold in the EU that allowed them to cheat on pollution control tests . A Department of Justice spokesman declined to comment. According to the EPA , software algorithms fitted to the VW cars can detect when the car 's emissions are being tested , by turning on pollution controls that cut nitrogen oxides from being pumped out of the exhaust . Volkswagen faces an $ 18bn penalty over the device , which has been cheating the clean - air standards during official emissions testing .
Following the Transport and Environment 's study that ﻿we reported last week , which claimed that 80 % of new diesel cars exceed EU pollution limits as manufacturers had been making alterations to cars in order to pass emissions tests ; the Environmental Protection Agency ( EPA ) has accused Volkswagen ( VW ) of installing software on cars sold in the EU that allowed them to cheat on pollution control tests . According to the EPA , software algorithms fitted to the VW cars can detect when the car 's emissions are being tested , by turning on pollution controls that cut nitrogen oxides from being pumped out of the exhaust . Volkswagen faces an $ 18bn penalty over the device , which has been cheating the clean - air standards during official emissions testing .