Instrument panel assembly and vehicle comprising the assembly

There is a casing (12), similar to an electric junction box, connected to the flanges by free-able retainers (26a,28b,38b) for causing the movement of this casing w.r.t the flanges under the action of a constraint, greater than a determined threshold, but maintains the casing w.r.t to the flanges when the casing is subjected to stresses less than the pre-determined threshold. The dashboard assembly (1) includes a structural element (2) extending along a longitudinal direction, flanges (4a) in the same material as the structural element, and extending perpendicularly in the longitudinal direction.