To provide a comprehensive and balanced perspective, the review also acknowledges well-established mainstream alternatives, including induction motors (IMs), which have demonstrated practical viability in commercial EV applications such as Tesla’s early production models. Variable flux motors (VFMs) have emerged as a transformative technology for new energy vehicle propulsion systems, addressing the fundamental trade-off between low-speed torque capability and high-speed efficiency that constrains conventional permanent magnet synchronous motors (PMSMs). This review systematically examines the structural design aspects of variable flux motors, encompassing hybrid permanent magnet topologies, magnetization state control mechanisms, flux regulation strategies, and electromagnetic optimization methodologies. Particular emphasis is placed on variable flux memory machines (VFMMs) employing low-coercive-force (LCF) magnets such as AlNiCo in combination with high-coercive-force (HCF) neodymium-iron-boron (NdFeB) magnets, as well as novel rotor shifting mechanisms and variable leakage flux designs. The paper synthesizes recent advances in series and parallel magnetic circuit configurations, swiveling magnetization techniques, and multi-objective design optimization frameworks. By analyzing comparative performance metrics across different VFM architectures and identifying persistent technical barriers including magnetization state control precision, demagnetization resistance, and manufacturing complexity, this review aims to provide a comprehensive reference for researchers and engineers engaged in next-generation wide-speed-range electric propulsion system development.