In Germany are two colour scheme: the green/white and the blue/white (or silver, which is the basic colour of the new vehicles). What is the reason, why both of two scheme are in use at the same time? Because I think it may cause problems for the people or foreigners. (Sorry for my bad english)
That`s very, very difficult. The colour depends on the state. We have 16 states and some states use blue stripes, other states use green stripes. The state of Saxony-Anhalt has both colours - silver/blue Mercedes E-class for the Highway-Sections, silver/green C-class as patrol cars. Our federal police ("Bundespolizei"; former "BGS") owns silver/blue cars. Bavarian police uses silver/green, but the green is brighter than the green in the other states. "Federalism" at it`s best, anno 2006.