Michael Caine decided to appear in 'Cars 2' for his grandchildren.
The British star – who voices Finn McMissile in the animated movie – wanted to be able to show the younger members of his family what he did but realised he couldn't show them some of his more adult-themed films.
He said: "When they ask what their granddad does, they can't see him in anything. (They) don't want to say 'Harry Brown' - It's not family viewing. When they offered me the chance to play the part of a car, I was very interested."
The 78-year-old actor also reveals he is one of only a handful of people to have seen the final script for forthcoming Batman movie 'The Dark Knight Rises', with director Christopher Nolan entrusting it to him to read.
Caine – who plays butler Alfred in the film, told Empire magazine: "I've read the new Batman script. Chris is the most secretive person. He said to me, 'You're one of only four people who have the end.' I daren't say a word about it or else I'll get fired."