See also:

Unlocking the driver's door (mechanical key)
If the vehicle can no longer be unlocked with the SmartKey, use the mechanical key. If you use the mechanical key to unlock and open the driver's door, the anti-theft alarm system will be trigg ...

4MATIC (permanent four-wheel drive)
4MATIC ensures that all four wheels are permanently driven. Together with ESP® and 4ETS, it improves the traction of your vehicle whenever a drive wheel spins due to insufficient grip. WARNING&nb ...

Please bear the following in mind
At the onset of winter, have your vehicle winterproofed at a qualified specialist workshop, e.g. at an authorized Mercedes- Benz Center. Observe the notes in the "Changing a wheel" ...