A method for forming a reflective element for a vehicular interior rearview mirror assembly includes providing a roll of an ultrathin glass sheet, the ultrathin glass sheet having a thickness dimension of less than or equal to 0.8 mm and greater than or equal to 0.3 mm. An elongated sheet of transparent plastic material if formed. The elongated sheet has a planar first side and a planar second side opposite the planar first side and separated from the planar first side by a thickness of the elongated sheet. The ultrathin glass sheet is unrolled from the roll of the ultrathin glass sheet and the unrolled ultrathin glass sheet is applied to the first side of the elongated sheet. A reflective layer is applied to the second side of the elongated sheet.