Volkswagen Chief Executive, Matthias Muller has a big day ahead of him as he meets Gina McCarthy, the head of the US Environmental Protection Agency which blew the whistle on its software cheating device for diesel emissions last year.

Mueller is on a tour of the US and so far it hasn’t been going well. The Californian Air Resources Board yesterday rejected Volkswagen’s initial plan to fix the diesel cars equipped with the controversial software, as "incomplete, falling far short of the legal requirements and incapable of being implemented quickly enough." The Californian position is supported by the EPA.

Mueller is now taking every media opportunity to apologise for his company’s failings in the US, following his first broadcast exchange on Monday where he denied the company had lied in evading emissions.

He later asked to repeat the interview claiming he had failed to hear the question properly due to noisy background conditions.

Here is the transcription with the exchange with National Public Radio (NPR):

NPR: You said this was a technical problem, but the American people feel this is not a technical problem, this is an ethical problem that's deep inside the company. How do you change that perception in the US?

Matthias Mueller: Frankly spoken, it was a technical problem. We made a default, we had a ... not the right interpretation of the American law. And we had some targets for our technical engineers, and they solved this problem and reached targets with some software solutions which haven't been compatible to the American law. That is the thing. And the other question you mentioned — it was an ethical problem? I cannot understand why you say that.

NPR: Because Volkswagen, in the US, intentionally lied to EPA regulators when they asked them about the problem before it came to light.

Mueller: We didn't lie. We didn't understand the question first. And then we worked since 2014 to solve the problem. And we did it together and it was a default of VW that it needed such a long time.