Thanks for the replies, Jim and Larry.
The vacuum explanation makes perfect sense.
The signal lights...Are German drivers then required to keep these lights on all night long if parked on the street? Or are they only permitted to park on the street for a short period of time? I've always been concerned about draining the battery by leaving those on and I live in Southern California where it never gets very cold. I can't imagine leaving the signal lights on all night in a very cold climate.

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Dave
1995 C280
1999 Triumph Daytona 955I - my speed fix.
1982 300TD - Gone, but not forgotten.