In 2015, the Environmental Protection Agency discovered that Volkswagen had fitted its vehicles with software that enables them to show false emission test results. More than 500,000 and 10 million Volkswagen diesel cars were found to have been installed with the software in the U.S. and global markets, respectively. The discovery came when Volkswagen had based marketing its vehicles in the United States on clean diesel, proving its deliberate intent to cheat. As a result, the company was enjoying 70 percent of the U.S. market share in diesel passenger-car.
The company admitted that it had violated the federal law on emissions by fitting the defeat device in its twelve models of diesel cars. Following the admissions, various lawsuits have been initiated in the U.S., resulting in various compensation packages for different models of the cars, imprisonment, fines, and penalties against the company and its former employees.