System limits

If the limit of the functional range is reached, the driver is prompted to act (brake or swerve).

During operation, the following system functions requiring explanation (for the driver) can occur due to the limits of the functional range:

• Limited range and deceleration: 
  • The range of the ACC sensor is limited (approximately 120 meters).

    Rain, snow and fog absorb radar waves.

    This will significantly reduce the range of the ACC sensor.

  • The Active Cruise Control option is only able to effect limited deceleration via the DSC (dynamic stability control) (a maximum of 2.5 m/s2; E65, E66: a maximum of 2.0 m/s2). This means that cruise control is only able to compensate for a limited relative speed.

  Operation of the Active Cruise Control is only possible in flowing traffic in a road speed range from 30 km/h to 180 km/h.

• Lateral monitoring range 

  The lateral monitoring range of the ACC sensor is limited, meaning that a monitored vehicle ahead could be lost due to a tight bend.

  In such cases, cruise control will not accelerate to the set speed for approximately 2 seconds. This will prevent the vehicle from accelerating too close to the vehicle ahead, which is possibly only briefly not being monitored.

  When driving straight ahead, this can cause a delayed reaction to another vehicle cutting in close in front. The vehicle cutting in will not be monitored by the cruise control until it is clearly in the same lane as the vehicle with the Active Cruise Control option.

• Display for monitored vehicle does not light up, the vehicle remains below the set speed and does not accelerate further. 

  Causes:

  • On sharp bends, the vehicle's speed will be controlled in such a way that lateral acceleration does not exceed a maximum of 4.0 m/s2 to maintain driving comfort.
• Timed separation less than 1 second 

  The timed separation from a vehicle driving ahead is no less than 1 second in the adjusted status. In certain conditions (e.g. when a vehicle cuts in a short distance ahead), this timed separation may briefly be less than 1 second.

  If the deceleration induced by the cruise control is not sufficient, the driver will have to intervene directly.

• ACC sensor blind 

  If the ACC sensor is blinded, the Active Cruise Control option shuts down. (Blinding, e.g. due to extremely heavy snowfall, through a layer of ice on the sensor or through dirt)

  Cruise control can be reactivated after the ACC sensor has been cleaned.

• Bends cannot be detected in an anticipatory manner 

  The cruise control is unable to work in an anticipatory manner when the vehicle is cornering. It is only able to react to existing lateral acceleration when it is already on the bend. For this reason, the driver is responsible for ensuring that an appropriate speed is being driven as the vehicle enters the bend.

• Active Cruise Control deactivated after DSC intervention or brake application by the driver 

Cruise control will be deactivated following DSC intervention or a brake application by the driver. (DSC intervention in the sense of enhanced operating stability.)

Cruise control will then have to be reactivated at the cruise control steering-column stalk.