See also:

Tire age
Tires degrade over time, even when they are not being used. It is recommended that tires generally be replaced after 6 years of normal service. Heat caused by hot climates, frequent high loading c ...

Low battery voltage
If the battery voltage is too low, the parking brake cannot be applied or released. Connect an auxiliary battery if the battery voltage is too low, see page 114. ...

Using voice commands
The driver initiates a voice command dialogue by pressing the voice control button (see the illustration on page 241). When a dialogue has been initiated, commonly used commands will be shown i ...