News of Martin Winterkorn's resignation Wednesday comes days after the automaker admitted that 11 million of its cars were rigged to cheat on EPA emissions tests. DANIEL ROLAND/AFP/Getty Images

UPDATE: 11:20 a.m. EDT -- Volkswagen Group CEO Martin Winterkorn issued a statement after resigning Wednesday amid an emissions-rigging scandal that has sparked worldwide investigations centered on the levels of pollutants emitted by the company’s diesel-powered vehicles. “As CEO, I accept responsibility for the irregularities that have been found in diesel engines and have therefore requested the supervisory board to agree on terminating my function,” Winterkorn said in the statement. “Volkswagen needs a fresh start ... I am clearing the way for this fresh start with my resignation.” He said he was “stunned that misconduct on such a scale was possible in the Volkswagen Group,” and he also said he “was not aware of any wrong doing on my part.”

Original story:

Volkswagen Group CEO Martin Winterkorn resigned Wednesday amid an unfolding scandal centered on company-made vehicles that were rigged to pass U.S. Environmental Protection Agency emissions tests by faking the levels of the pollutants they produce in an effort to make them appear more environmentally friendly, CNBC reported. Winterkorn is expected to be replaced by Matthias Mueller, an executive at Porsche, Reuters said Tuesday, citing local German media.

News of Winterkorn’s resignation broke after the company admitted Tuesday that 11 million of its cars had been affected by the software, more than 20 times the initial estimate of 500,000 cars announced Friday. Volkswagen AG’s share price continued to drop this week, plummeting 20 percent to a four-year low.

Winterkorn released a video statement Tuesday saying he was “endlessly sorry we betrayed the trust of customers.” He pledged: “We are going to clarify the background unsparingly, and, at this very moment, everything is being put on the table as quickly, thoroughly and transparently as possible.” He added: “The irregularities with these engines contradict everything for which Volkswagen stands. To make it very clear, manipulation at VW must never happen again.”

Last year, Forbes business magazine ranked Winterkorn No. 58 on its list of the world’s most powerful people, ahead of the leaders of Mexico and Japan. Forbes said at the time that he “urged European regulators not to overburden the automotive industry with excessive emission targets, citing a lack of time to develop fuel-efficient technology and the economic downturn as major concerns.”