"On behalf of our company, and my colleagues in Germany, I would like to offer a sincere apology for Volkswagen's use of a software program that served to defeat the regular emissions testing regime," said Michael Horn, president of Volkswagen Group of America in a hearing held by the House Committee on Energy and Commerce.

　　However, he asserted top corporate officials had no knowledge of the cheating software installed in 11 million diesel cars in the emissions scandal enveloping the world's largest automaker.

　　"To my understanding this was not a corporate decision, this was something individuals did," Horn said, noting that he felt personally deceived.

　　Volkswagen U.S. chief apologizes for emission cheat, giving no remedy schedule

　　On Sept. 18, the U.S. Environmental Protection Agency (EPA) issued a Notice of Violation (NOA) of the Clean Air Act to Volkswagen (Volkswagen AG, Audi AG, and Volkswagen Group of America) accusing the company of installing a software to evade authority's emission control in about half million diesel cars sold in the United States since 2008.

　　The software called "defeat device" by the EPA can turn on full emission controls only when the car is undergoing emission tests to make the car meet the legal emission standards, but during normal driving, the car will emit nitrogen oxides at up to 40 times the standard.

　　Horn said Volkswagen will "take full responsibility" for this illegal action and is "working with all relevant authorities in a cooperative way."

　　"Our immediate goal is to develop a remedy for our customers," said Horn, but he declined to release the timetable for the company to make the remedy when Dianna DeGette, Representative from Colorado asked him.

　　"We are still working on the time frame (of the remedy) and it's too early to say when this fix is exactly going to take place," said Horn.

　　Horn said Volkswagen has already begun a world-wide investigation into how these matters happened and identified responsible parties. But he said, "Any information developed at this stage is preliminary."

　　The EPA has also continued its investigation into Volkswagen's action, working closely with the California Air Resources Board and the U.S. Department of Justice, said Christopher Grundler, director of EPA's Office of Transportation and Air Quality at the hearing.

　　"However, at this point we are unable to provide further details of the investigation because the release of such information could jeopardize this onging enforcement investigation," said Grundler.

　　Volkswagen could face a total of more than 18 billion U.S. dollars for this scandal as the highest penalty per car for violating the Clean Air Act is 37,500 dollars, according to the EPA.

　　Since the EPA issued the NOV to Volkswagen, the price of the company's share has fallen sharply and it former CEO of Volkswagen AG Martin Winterkorn has resigned for it.

　　Many governments in Europe and Asia where Volkswagen sells diesel cars have also started to investigate into the company.