Lightweight, thermoplastic, vehicle headliners each having at least one integrally-formed, energy-absorbing, head-impact mechanism and injection molding methods for making same are provided. Each headliner includes a stiff, self-supporting, thermoplastic sheet adapted to be mounted adjacent a roof of the vehicle so as to underlie the roof and shield the roof from view. The sheet has an upper surface and a lower surface. Each energy-absorbing, head-impact mechanism absorbs energy of an impact with its associated headliner by a passenger of the vehicle. In one embodiment, the at least one head-impact mechanism includes a plurality of spaced-apart, energy-absorbing, thermoplastic structures, such as ribs, which are connected to and extend upwardly from the upper surface of its thermoplastic sheet. In another embodiment, the at least one head-impact mechanism includes a fabric or other material having a foam backing bonded to the lower surface of the thermoplastic sheet to create a cosmetically-acceptable appearance for the headliner and which is compressed by a passenger of the vehicle to absorb energy of the impact. In yet another embodiment, the at least one head-impact mechanism includes a series of tubular voids formed in the thermoplastic sheet and which are compressible for absorbing energy of the impact. Each headliner also preferably includes at least one attachment mechanism such as a hollow, plastic grab handle integrally formed with its thermoplastic sheet.