Volkswagen CEO Martin Winterkorn resigned on Wednesday, taking responsibility for the German carmaker's rigging of U.S. emissions tests in the biggest scandal in its 78-year history.

"Volkswagen needs a fresh start — also in terms of personnel. I am clearing the way for this fresh start with my resignation," Winterkorn said in a statement.

He said he was shocked by events of the past few days, above all that misconduct on such a massive scale was possible at the company.