The subject invention provides a thermoset elastomer comprising a crosslinked pseudorandom or substantially random interpolymer of: (a) from 15 to 70 weight percent of monomer units derived from at least one a-olefin, (b) from 30 to 70 weight percent of monomer units derived from at least one vinylidene aromatic compound, and (c) from 0 to 15 weight percent of monomer units derived from at least one diene. The subject invention further provides a thermoplastic vulcanizate comprising the thermoset elastomers of the invention as provided in a thermoplastic polyolefin matrix. The subject invention further provides processes for preparing the inventive thermoset elastomers and thermoplastic vulcanizates, as well as parts fabricated therefrom. The inventive materials have a superior balance of properties, as compared to EPM and EPDM based materials. The subject invention also pertains to foams and methods for their preparation.