Muller has already tested the C-Elysée, Citroën’s new WTCC racing car at the Circuit Paul Ricard in the South of France.
“It’s really terrific. I think we will be able to do great things with it,” he said in a film released by the French manufacturer.
Muller had surely played a role in Citroën’s decision to join WTCC, because he had invited Loeb to test his Chevrolet Cruze two years ago at Rockingham.
Now he will find himself to form a dream pair with Loeb. Together they boast an impressive loot of 12 FIA world titles, which may soon become 13 as Muller is just one step away from being crowned WTCC champion for the fourth time.
“I am really honoured to represent the colours of Citroën. It’s fantastic that a brand that has won so much in motor sport has decided to join a category where it needs to learn everything," Muller added.
"And this is a great motivation for me, as I can bring my experience and give my contribution to build a successful programme."
RML thanked the French driver for his four successful years with the team in WTCC.
Ray Mallock, RML chief executive said: “Naturally everybody at RML will be sorry to see Yvan go at the end of this year – he has been a key supporter and a perfect ambassador for RML over the very enjoyable years that we have worked with him.
"However, we appreciate this will not have been an easy decision for him to make and we fully support Yvan in his move and wish him the best of luck for the future. I am tremendously proud of our achievements.”
Speaking about the future Mallock said: “Our short term goals are clear; we are focussed on ensuring our 2013 campaign ends on a high note, with another World Title for Yvan and the team.
"In the longer term RML Group will continue to bring success in which ever formulae it competes in, and we hope to return to the new-specification 2014 WTCC, one way or another.”