There you go, for sale from the German government:

http://www.vebeg.de/web/de/verkauf/browse.htm?DO_SUCHE=1&SUCH_KAT=MDJhIFNvbmRlcm- ZhaHJ6ZXVnZSAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICMgU3- BlY2lhbCBWZWhpY2xlcw==&statflag=1&SHOW_AUS=84812

It's unusual at the VEBEG, but here they haven't remarked the licence-plate. Before the GSG 9 and other special forces have used them for driver's trainings, these cars were surely used by the top politicans like chancellor, president or so - a Mercedes S 500 or a BMW 750 iL, armoured and with flag-holder, were surely not used by sub-positioned bureaucrats.

I'm not especially interested in armoured cars, but I do like W140s, and I really like E38s.
Interesting finds, thanks.