I have used WD-40 for years to remove duct tape residue from the fibreglass of my various sailboats and their plexiglass windows.   Check with the manufacturer to see if there is anything in the formulation that would harm your windshield.   If OK to use, it will melt the stuff right off and then you can use a plexiglass cleaner to remove the fine film WD-40 deposits.

Harry League

Ron Raby wrote:

to everyone: I have some ducktape residue on my windsheild. I want to get some info on cleaners or chemicals I can use to remove this without damaging the surface. Thanks Ron Raby Lancair ES Painting 90%