Niki Lauda, the subject of the Formula One film Rush, talks to John Hiscock about his great rival James Hunt and explains why he agreed to the film.

Former Formula One world racing car champion Niki Lauda estimates he has been approached 30 times over the years by people wanting to tell his story.

But it was not until the British playwright and screenwriter Peter Morgan (The Queen, Frost/Nixon) contacted him that he finally agreed. "Oscar nominations, good writer, top man," he told me succinctly when we talked at the Toronto Film Festival. "I started talking to him and he developed the story about the 1976 racing season and the rivalry between me and James Hunt."

The result is Rush, which had its premiere in Toronto and is being widely viewed as a possible Oscar contender. The Australian actor Chris Hemsworth does a creditable job portraying Hunt, the hard-living, fast driving playboy who died of a heart attack in 1993 aged 45, while Daniel Brühl, who is also in the Julian Assange story The Fifth Estate, portrays the methodically brilliant Lauda.