I replaced one of the rear fenders without removing the roof on my 2005 CDN Z4.
How? - Used a small and short 1/4 inch wrench and a 1/4 torx bit cut in half and filed to smoothen out edges. Then with the roof down, and rubber pulled back around the fender, simply slip the torx bit in the screw, and the bit stays in place due to the roof canvas. Using the open end of the wrench turn the screw loose, and remove by hand.
Easy Peazy.
How? - Used a small and short 1/4 inch wrench and a 1/4 torx bit cut in half and filed to smoothen out edges. Then with the roof down, and rubber pulled back around the fender, simply slip the torx bit in the screw, and the bit stays in place due to the roof canvas. Using the open end of the wrench turn the screw loose, and remove by hand.
Easy Peazy.