Formula-1 racing fans in Berlin are expressing shock at Nico Rosberg's unexpected announcement that he is retiring.

"That's going to be a loss to the sport. That's going to be a big loss to the sport because he was such a wonderful part of it for so many years. "

"Why not? It's his decision. When he thinks that's right. Why should he gamble with his life?"

"Pity no? He could have done more. But in the end, I see it similarly, if he finds it right, that's what he should do. To go out as world champion, could be worse."

Rosberg, who had given no previous indication of his intentions, says he made his decision to retire from F1 just a day after winning his first Driver's Championships after the final race of the year in Abu Dhabi.

He will leave Formula-1 after winning 23 of the 206 races he competed in,9 of which he won this year.

Rosberg narrowly held off his Mercedes teammate Lewis Hamilton for this year's Driver's Championships.

It's unclear if their notably sour relationship has anything to do with Rosberg's decision to retire, as he had been signed with Mercedes through the 2018 season.

The 31-year old contends his main reason for retirement is to spend more time with his family.