Michael Caine decided to appear in Cars 2, in which he voices Finn McMissile, for the sake of his grandchildren.
According to ContactMusic, the two-time Oscar winner 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 has also spoken about being one of the chosen few to have seen the final script for director Christopher Nolan’s Batman movie The Dark Knight Rises.
In an interview with Empire, Caine, who plays butler Alfred in the film, said: "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."
