Fastening device to a ventilation grid in a vehicle and related utiliser system

A fastening device to a ventilation grid of a vehicle is disclosed, comprising a removable-connection body for attachment to said grid and a plurality of fastening elements, wherein said connection body (1) is coupled with a spongy spacer (2) and said fastening elements are retaining laces (3) suited to constrain said connection body (1) to said grid with the spongy spacer (2) partly compressed therebetween, the connection body (1) furthermore comprising a hollow joint head (1b) with which a utiliser accessory (4, 6) may be engaged, an airway being defined through said spongy spacer (2) and said joint head (1b), then leading into said utiliser accessory (4, 6).