Methods for making compositions for making thermoplastic aliphatic urethane/urea elastomers, which are in turn used to make molding compositions used in forming molded articles, particularly, shells for automotive applications. The molding compositions comprise an aliphatic thermoplastic urethane/urea elastomer and a polyolefin-based modifier. These compositions may be used to form a powder, pellets, microspheres or minibeads which may then be cast to form air bag door and instrument panel cover skins which may meet automotive deployment and weathering requirements.