Volkswagen’s chief executive Matthias Mueller said in an interview with a German newspaper that the company would launch a recall for cars affected by its diesel emissions rigging in January and complete the fix by the end of next year.

“If all goes according to plan, we can start the recall in January,” Mueller told the Frankfurter Allgemeine Zeitung. “All the cars should be fixed by the end of 2016.”

Mueller also told the newspaper that he believe only a few employees were involved in the diesel emissions rigging that has hammered the company’s stock and done severe damage to its reputation, refuting the notion that his predecessor Martin Winterkorn may have known about it.

He said VW would have to become slimmer and more decentralised, saying every model and brand would be closely examined for its contribution to the company. But he said an “evolution” rather than a “revolution” was needed to get VW back on track.

Mueller also rejected the suggestion that VW had informed financial markets too late about the diesel problems despite having told officials at the US Environmental Protection Agency weeks before it went public.

The company also apologised for its emissions scandal in a letter to US customers obtained by Reuters on Tuesday, but the German carmaker said a remedy would take time.

“I am writing you today to offer a personal and profound apology. Volkswagen has violated your trust,” read the letter written by the head of the German company’s US arm, Michael Horn, which was dated 29 September.

Horn said the company was working hard on remedies to bring cars into emissions compliance as soon as possible but “getting this right will take some time”.