Additional info in regards to silver:
Germany was asigned 'white' as its national racing color, as part of the
Gordon Bennett races - silver came into play in the '30s, first with Auto Union then M-B. And M-B resorted to Silver to make weight, I beleive in '35.
A decent history of the Silver Arrows is available in a book written by Chris Nixon (no longer with us unfortunately) titled, simply,
"Racing the Siver Arrows".
(The wiki entry linked under 'Gordon Bennett' is wrong in regards to Italy's color being red - it was black originally - I need to do more digging to run that one down.)