For more than a year, Volkswagen executives told the Environmental Protection Agency that discrepancies between the formal air-quality tests on its diesel cars and the much higher pollution levels out on the road were the result of technical issues, not a deliberate attempt to deceive Washington officials. But early this month, Volkswagen executives finally made a startling admission: The diesels it sold in the United States used software deliberately designed to cheat on the tests. The company was evidently concerned that actually meeting the federal emissions standards would degrade the power of the diesels, which it marketed as comparable in performance to gasoline engines. Meeting the standard would also undercut the fuel efficiency that is one of […]