I know, old thread
So what...... I have good advice.
To remove tree sap I use 3M Adhesive, Tar, and Grease Remover. I found it at Advance Auto Parts but check out all your local auto parts joints for it. It comes in an aerosol container.
This works great on sap and tar. But be sure to wash your car after using it. You don't want the residue to sit on the paint.
If you're a risk taker try something like mineral spirits or naptha to remove sap. This stuff can be bought at Home Depot or the auto paint section of your auto parts stores. Be careful with this. Test it on an inconspicuous place on your car to make sure it doesn't remove the paint. Wash your car after using it. Naptha and mineral spirits are what body shops use to remove silicone oils and wax from cars before painting them. So they don't care what kindo of damage it does to the paint; the car's being repainted anyway. But it will remove all kinds of shit from your paint.