See also:

Additives
Only use DEF in accordance with ISO 22241. Do not use additives with DEF and do not dilute DEF with water. This may destroy the BlueTEC exhaust gas aftertreatment system. ...

Important safety notes
WARNING When leaving the vehicle, always remove the SmartKey from the ignition lock. Always take the SmartKey with you and lock the vehicle. Do not leave children unsupervised in the vehicle ...

Switching the rear-compartment climate control on/off using the front control panel
Turn the SmartKey to position 2 in the ignition lock. Activate the rear compartment function via COMAND. The rear-compartment climate control can be controlled via the front control panel ...