Volkswagen's US head said on 21 September in New York he was confident the German carmaker would take the necessary steps to restore customer confidence after it "totally screwed up" by rigging emissions tests of diesel-powered vehicles in the United States.

Michael Horn vowed to make amends at a lavish event in New York to promote the 2016 Passat saying the German carmaker is "committed to do what must be done and to begin to restore your trust."

"The CEO of our parent company Martin Winterkorn said yesterday Volkswagen will fully cooperate with the responsible agencies and much much more important as I see it, he stated that he was personally and deeply sorry for this, that Volkswagen has broken the trust of our customers and the public here in America," said Horn.

"And lastly he stated that this matter, and I think this is common sense, now is the first priority for him personally and for the entire board of management. So let's be clear about this, our company was dishonest with the EPA and the California air resources board, and with all of you, and in my German words, we have totally screwed up. We must fix those cars and prevent this from ever happening again and we have to make things right with the government, the public our customers, our employees and also very important, our dealers," he added.

The comments from Horn, chief executive of VW's US unit, came after the US Environmental Protection Agency (EPA) said on 18 September that Volkswagen, the world's biggest carmaker by sales, used software that deceived regulators measuring toxic emissions and could face penalties of up to $18bn (£11.62bn).

Volkswagen shares plunged nearly 20 percent on Monday after the carmaker admitted it had rigged emissions tests. German government officials have expressed concern that the scandal could damage the reputation of its car industry, and the US Department of Justice began a criminal probe of the effort to game the emissions tests, according to press reports. German officials urged Volkswagen to fully clear up the matter and said it would investigate whether emissions data had also been falsified in Europe.

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