There's no law in the U.S. that says the turn signals have to be amber....while overseas it's mandatory that they are. Manufactures that sell cars overseas and in the states find it easier to have them amber and only make one lense for both here and there. I had to change my turn signals in my Vette to amber (see pic below)when I took my car to England and then left them that way when I returned. When the newer Vettes are exported overseas GM actually change the tail lights to conform to the laws.
