Tunnel detection*
In markets without automatic dipped beam, tunnel detection activates dipped beam when driving into a tunnel. Dipped beam is deactivated approx. 20 seconds after the car has been driven out of the tunnel.
The tunnel detection function is available in cars with rain sensor*. The sensor detects the entrance to a tunnel and resets the lighting from daytime running lights to dipped beam. Approx. 20 seconds after the car has left the tunnel, the lighting returns to daytime running lights. If the car is driven into another tunnel within this time period then dipped beam is kept switched on. This avoids repeated changes to the car's light settings.
Note that the headlamp control's knob must remain in 
position for tunnel detection to work.