Removing tree sap from a car's finish is a problem that we deal with on a regular basis. We've found that by hand-buffing the sap droplets with rubbing alcohol, we're able to remove the sap pretty well because the alcohol acts as a solvent to break up and dissolve it. For some cars, though, removing the sap can require a good deal of work, especially when there is a large amount of sap, or when it's obvious that the sap has been left on the finish for an extended period of time. For these cases, we experimented to find a quicker, easier method of sap removal. By hand buffing the sap-covered areas with a light-duty compound, we remove the hardened "shell" on the sap droplets. Then we use the rubbing alcohol. The light-duty compound helps to soften up the sap-covered areas so that the rubbing alcohol can dissolve the droplets faster and with less effort.  

This method also allows the detailer to apply less pressure on the droplets, so there's less change of scratching the area. Once the sap has been completely removed, we buff the surface again with light-duty compound to clean up any marks that might have been made during the hand-rubbing stage. The last step is to apply a coat of wax with a foam pad for a deep shine without any swirl marks. We then recommend that the customer park their car in a different spot, away from trees that leap. 

Other alternatives:  

I have used the following things to remove tree sap, in this order:

• Bug and tar remover (carried at any auto shop, in an aerosol can)
• Kerosene and a rag (put kerosene on rag, dab sap spot repeatedly)
• Gasoline and rag (same procedure as kerosene) As soon as the sap is removed, wash the area with soap and water, then wax it.

Start with the bug and tar remover, this is the mildest of the three.