According to Juan Luis Iborra and Yolanda García Serrano, Km. 0 is a mid-summer afternoon's dream, full of fairy godmothers. Everyone mends everyone else's life… well, almost everyone's.

The idea for the film came from living so close to the seething mass of people who frequent Madrid's central point, Puerta del Sol, and also from the question: what would happen if people make mistakes and, as if by magic, those mistakes become life-changing events?

The heat of summer encourages human contact and eroticism. While at the same time, the variety of characters helps to make the film fresh; not a continuous belly laugh, but charming and very much an actors' film.

The challenge was having to shoot at the actual location of Km.0 at the Puerta del Sol. It was a nightmare, done against the clock, under the steely control of the police who had to stop the traffic and deal with the traffic jams.