Thermoplastic compositions including component C, an ethylene/α-olefin interpolymer wherein the interpolymer has a Mooney Viscosity (ML 1+4, 125° C.) greater than, or equal to 55 and a ΔHf greater than, or equal to 36 J/g; and component D, a high density polyethylene (HDPE) are provided. In particular, the thermoplastic compositions are characterized by the ethylene/α-olefin interpolymer which is an ethylene/a-olefin/diene interpolymer having a rheology ratio (V0.1/V 100) at 190° C. greater than, or equal to 25. Also are provided the articles comprising the thermoplastic compositions.