Depending on the selected recuperation level, the electric motor is operated as an alternator when in overrun mode and during braking in order to charge the high-voltage battery while driving. As soon as you release the accelerator pedal when the vehicle is in motion, recuperation in overrun mode is initiated.
supports braking with an electronically controlled brake force boosting
converts the kinetic energy of the vehicle into electric energy
In the 
drive program, you can use the steering wheel gearshift paddles to manually adjust the intensity of recuperation in overrun mode More.
when the high-voltage battery charge level increases
if the high-voltage battery is not yet at a normal operating temperature
when driving at speeds close to zero
in transmission position
during and after ESP® intervenes
In these cases, the desired deceleration is set by the brake control system. Also brake with the service brake if necessary.