It is commonly known that controlling motor speed is the most efficient way of capacity control in e.g. HVAC systems. However, making sure that the motor itself runs in the most efficient operating point can be challenging, as it would require extensive knowledge of the motor parameters, including non-linear or saturation effects, over a wide operating envelope. Furthermore, indirect factors such as ambient temperature or ageing effects could likewise complicate matters. In this paper, it is shown that the efficiency of a converter driven motor may be increased when deviating from the operating point dictated by nominal parameters. Both asynchronous and synchronous motors are considered. Considering the volume of inverter driven motor systems worldwide, it is shown that even small improvements can bring substantial energy savings in a larger context.