How do you size the powertrain components for a plug-in hybrid vehicle?

PHEV component sizing involves: Defining pure electric range target (determines battery capacity, typically 8-15 kWh), motor sizing for pure EV performance requirements, engine sizing for sustained high-speed and grade climbing, transmission ratio selection for both EV and HEV modes, thermal system capacity for fast charging and sustained performance, and charging system power level. Trade-offs include weight, cost, package, and performance across modes. Simulation across regulatory drive cycles (WLTP, EPA) plus customer usage profiles validates sizing. Battery oversizing provides degradation margin for warranty period. The design must meet both EV-mode and hybrid-mode performance targets.