Electromechanical power steering.
The electromechanical power steering system is only active when it’s needed: when you’re turning the wheel. It draws electrical power from the battery, which Brake Energy Regeneration converted from the vehicle’s braking and kinetic energy.
This element of BMW EfficientDynamics replaces the conventional hydraulic power-steering system with an electric motor. While hydraulic systems constantly draw power from the engine – thereby consuming extra fuel – the innovative BMW system only springs into action when it's actually needed. If you don't move the steering wheel (on a straight, for example, or on a steady curve), the electric motor remains inactive and therefore requires no energy.