VW chief says he is "deeply sorry" after EPA accuses firm of violating US clean air standards

The CEO of Volkswagen apologized Sunday after the Environmental Protection Agency said the German automaker skirted clean air rules by rigging emissions tests for about 500,000 diesel cars.

"I personally am deeply sorry that we have broken the trust of our customers and the public," Volkswagen chief Martin Winterkorn said in a statement. He said VW has ordered an investigation and promised that the company would cooperate with regulators.

The EPA said Friday that VW used software that allowed its diesel cars to release fewer smog-causing pollutants during tests than in real-world driving conditions. The cars, built in the last seven years, include the Audi A3, VW Jetta, Beetle, Golf and Passat models.

The agency ordered VW to fix the cars at its own expense. VW also faces fines.