A vehicle straddle seat has a base extending generally in a first direction from a first edge. A backrest, formed integrally with the base, is spaced from the first edge and extends away from the base in a second direction generally perpendicular to the first direction. The backrest includes a first surface facing generally towards the first edge and a second surface facing away therefrom. A plurality of ribs formed on at least one of the first and second surfaces extends at least in the second direction. The plurality of ribs is configured to allow flexing of at least a portion of the backrest with respect to the base towards the first edge and away therefrom. The first surface is rigidly connected to the second surface so that the first and second surfaces flex together with respect to the base. Latch mechanisms and vehicles having the seat are also disclosed.