My colleague said that the orange, "...is a symbol of wealth." He also stated that a combination of bay and olive represents victory. "Orange and bay/olive is usually a present for the Christmas (especially for the first visitor on Christmas morning). You keep them for all year, because bay and orange protect the family and house." This then suggests that people who adorn their vehicles with bunches of bay and olive leaves are proclaiming victory. Perhaps the victory in the season is that which is brought about by the birth of the Savior.