Well, at the time of this post, you made this request a little over a day ago. If you get to it quickly, you can wash it off. Meguiars NXT Generation car wash is amazing. They also have a Speed Detailer which is a mist and wipe product for you to use in between washes.
If the sap is dried up on your car, follow the suggestions made here and clay the car. Keep in mind however, that claying a car will remove not only all the dirt and grime, but any wax on the car as well. That said, after you clay, you need to polish (to shine) and then wax (to protect). I would also use a paint cleaner in between the claying and polishing steps.
You're probably asking yourself, "What brand?" Well, you'll get different answers from different people. Some good manufacturers are Mother's or Meguiar's. A lot of people on this site live and die by Zaino, but I've never tried so I can't give an opinion on their products.
I use 100% Meguiar's.
Quik Clay (I haven't clayed the Mustang yet because it really hasn't needed it yet)
Meguiar's 3-step system (Cleaner, polish, wax). Although I substitute step 3 and use the NXT Tech Wax instead. All these products are available at Pep Boys and the like.
Before you use any of these products, learn how to use them, especially the clay. Simply read the directions and you'll be set. There are plenty of websites that have how-to articles on car care. I'm not sure if the rules of this site will allow me to post them. Moderators??? If you want, PM me and I'll give you the sites.
Hope this helps
Then proceed to wash with whatever car wash you like. Safest route in my opinion.
