Just a thought, is there any special reason why MB went for the vacuum pumps instead of the electrical solenoids that other cars use? I would've thought solenoids were more reliable but I could be wrong...

 

It does seem kinda old-fashioned, and would be more so if the vacuum ran off the engine.

It reminds me of the "car phone" Jethro put in Pa's truck. It used a looooong cord.

 

to reduce noise.

 

They must have noisy solenoids in Germany. My SL is noisier than any car I've ever had with auto door locks. It "clunks" instead of clicks.

 

but before and now the vacuum/pressure pump also use other functions.

seat and backrest multi contour adjustment.

raising the rear headrests.

door closing aid (power closing).

trunk lid power closing.

actuating reverse guide bar (W140, S500).

aircon flap actuating element (now stepper motor).

they call it "combine" pump now.