A process for producing a thermoplastic vulcanizate, the process comprising: (i) charging a reactor with an oil-extended olefinic copolymer rubber, where the rubber is synthesized by a single-site catalyst, characterized by a multi-modal molecular weight distribution, and includes greater than 10 parts by weight extender oil per 100 parts by weight rubber; (ii) charging the reactor, contemporaneously or sequentially with respect to the rubber, with a thermoplastic resin, an oil, and a cure system to provide a pre-vulcanized mixture; and (iii) mixing the rubber, thermoplastic resin, oil, and cure system at a temperature above the melt temperature of the thermoplastic resin to thereby cause dynamic vulcanization of the rubber and produce the thermoplastic vulcanizate.