The German Federal Border Protection (Bundesgrenzschutz, BGS) started as a paramilitary force with a role to protect the borders of the Federal Republic of Germany. Later it developed more and more into a Federal police force, taking over the role of railway police (Bahnpolizei) as well. It is now the Bundespolizei (Federal Police).
Volkswagen Bus in old green overall:
Volkswagen Bus in lighter green overall:
Please note that these are scans from old 35mm slides from my archives, with resultant deterioration in colours and sharpness.