Hmm, if my head hit a car windscreen on the edge of the frame a cycle helmet would make **** all difference to the outcome, I would be dead.
As for my head hitting a car windscreen somewhere in the middle, BTDT, without a helmet. From memory, my head had one very small cut from a piece of glass stuck in the corner of my face.
UPDATED: The picture that was originally displayed showed the edge of a windscreen (broken) where the frame was dented.