From the Wikipedia page on the Bavaria Free State :
"The White-And-Blue Inescutcheon (Herzschild = "Heart Shield"): The escutcheon of white and blue oblique fusils was originally the coat of arms of the Counts of Bogen, adopted in 1247 by the House of Wittelsbach, The white-and-blue fusils are indisputably the emblem of Bavaria"
So all those BMW drivers are flying the colours of the Count of Bogen, whose subjects could reliably be described as Bogans! That won't sit well in Toorak or Mosman.

