Air improving apparatus for use in motor vehicles and cartridge for the air improving apparatus

The cartridge (16) holds a perfume substrate (79). The casing (12) is mounted behind the instrument panel (14) and includes an airflow opening (18). This is connected to ventilation openings (20) in the instrument panel. The cartridge has an outlet opening (22) corresponding with the airflow opening (18). It is arranged in the casing so that it can be moved from a closed position in which the outlet is blocked, to an open position in which the airflow opening lies over the outlet opening.