Motor Efficiency
Motor efficiency is the ratio of mechanical power leaving a motor shaft to electrical power entering the motor terminals at a specified operating point.
It is a map, not one number
Efficiency changes with motor speed, torque, temperature, voltage, and control strategy. Engineers therefore use an efficiency map rather than a single best-point percentage. Copper loss becomes important at high current, while magnetic and mechanical losses can dominate elsewhere.
The boundary matters: a motor-only result excludes inverter, reduction-gear, differential, pump, and battery losses. A motor-and-inverter or complete-drive-unit figure answers a different question. Motor control and efficiency maps EV motor testing and ratings
Motoring and regenerative operation can also have different maps. Vehicle consumption depends on how often the drive visits each operating point, not only on the highest efficiency printed in a specification.