Martin Winterkorn
Volkswagen Group boss Martin Winterkorn has apologised for his company deliberately cheating in US car emissions testsReuters

Volkswagen Group boss Martin Winterkorn said he is "endlessly sorry" for his company deliberately cheating in US car emissions tests and says such "manipulation" will not happen at VW again. However, he will remain in the job despite reports claiming he would be imminently replaced by Porsche CEO Matthias Müller.

"I am endlessly sorry that we have betrayed the trust [of VW customers]," Winterkorn said on 22 September. "Swift and comprehensive clarification now has the utmost priority. To make it very clear: manipulation at VW must never happen again... we will do everything to regain your confidence step by step."

In a video message recorded in German and published on VW's press site, Winterkorn said there would be a full investigation and he asked for forgiveness. He said it would be wrong to put the honest work of the company's 600,000 workers under general suspicion because of wrongdoing caused by a minority.

Ruthlessly investigating

"At this point, I don't have the answers to all the questions," Winterkorn said. "But we're in the process of ruthlessly investigating the issue, and to that end everything will be put on the table as fast, thoroughly and transparently as possible."

Winterkorn's apology comes just a day after US boss Michael Horn said the car maker had been "dishonest," had "totally screwed up" and would "pay what we have to pay."

The company has set aside €6.5bn (£4.7bn) to cover the cost of recalling up to 11 million vehicles worldwide, all of which are believed to use an engine that VW has deliberately programmed to cheat its way through strict US emissions tests by running differently during tests to how it does on the road.

Shares in Volkswagen were down almost 20% on 22 September - at €106 per share it's their lowest level in over four years. The value of shares in BMW and Mercedes also fell, as VW's cheating in emissions tests of diesel engines could have a far-reaching impact across the automobile industry.

VW emissions scandal explained in 60 secondsIBTimes UK

'Working at speed'

Volkswagen said it is "working at full speed to clarify irregularities concerning a particular software used in diesel engines." The company stated: "New vehicles from the Volkswagen Group with EU 6 diesel engines currently available in the European Union comply with legal requirements and environmental standards. The software in question does not affect handling, consumption or emissions. This gives clarity to customers and dealers."

VW has found that this engine management software is also found in other Volkswagen Group vehicles with diesel engines; it says for "the majority" of these engines the software does not have any effect. Volkswagen Group owns Audi, Seat, Skoda, Bentley, Bugatti, Lamborghini, Porsche, Ducati, and truck makers Scania and Man. For now, none of these other companies have been directly implicated in emissions cheating.

'We have totally screwed up'

Michael Horn, the boss of Volkswagen Group of America admitted his company has "totally screwed up". The car maker was investigated for deliberately cheating to pass US emissions tests. VW's US chief executive was speaking at the New York launch of the new Passat, set to replace a car accused of cheating.

Horn said: "Our company was dishonest. We have totally screwed up. We must fix the cars to prevent this from ever happening again and we have to make this right. This kind of behaviour is totally inconsistent with our qualities. We are committed to do what must be done and to begin to restore your trust. We will pay what we have to pay."