From now on, if your ‘Permiso de Circulación’ (logbook of the car & proof of ownership) is lost, stolen or just damaged, you can request a duplicate in any post office in Spain.
You don´t need to make an appointment and go to a Traffic Office any more. You only need to take your ID to the nearest Post Office and a provisional Permiso de Circulación will be issued.
Source: Dirección General de Tráfico – España