I have had several w211 cars with the factory nav system. Let me point out a few things about using it. It does not know individual street addresses, it only knows ranges. So it guides you to the block in which a house is located, but not the house itself. Address entry is by using the cursor up/down/right/left buttons and the OK button, it's not a touch screen and there is no voice recognition. So address entry is extremely tedious. It does not know as many gas stations, restaurants, etc. as newer systems.

During the last few years owning a w211 I used my iPhone and ignored the nav system - it was easier and faster to use, and worked better. My wife kept a garmin in the glovebox of her car and used that instead of the factory nav system.