Abstract: A multi-piece nestable fairing (20) for mounting on the roof (22) of a vehicle (24) is disclosed. The fairing (20) has lower and upper fairing members (26,28). The lower fairing member (26) is mountable to the roof (22) of the vehicle (24). The upper fairing member (28) is selectively translatable relative to and affixable to the lower fairing member (26) between a lowered nested position and a raised operative position thereby altering the overall height of the fairing (20). The lower fairing member (26) preferably has a support (44) configured therein so that the upper fairing member (28) may rest upon the support (44) with the upper fairing member (28) being affixable to the lower fairing member (26) in the raised operative position.