IE3 motors are now mandatory in Europe for new installations between 7.5 k W and 375 kW. This is in line with elsewhere in the world. (And for a time in Europe, IE2 motors with a variable speed drive may be used for drive-suitable applications)
IE3 motors are more efficient than IE2 motors. The improved efficiency results in lower lifetime energy usage and energy costs, which has obvious value. However, other IE3 motor characteristics are affected by the changes made to achieve this efficiency. For example, the starting torque is lower, and the starting current is higher.