Thanks for reaching out, Paul. First off, congratulations on the new car purchase! It’s great you actually get a parking spot with your apartment, that’s not always the case. Unfortunately, it’s not great that it’s under a tree.
Considering the bird poop, leaves, twigs, and sap that’s dropping onto the car, our first recommendation would be to stay extremely attentive and wash the car a minimum of once a week. Animal droppings, leaves, and sap could all eat away at the top layer of the paint that’s called the clear coat. If left on the car for extended periods of time, the damage will leave a visible stain of sorts, especially if it’s baked in the sun at various points in the day. That means you should clean all of these things, even the leaves, off your car as soon as you can. The longer they stay on, the harder they will be to clean, and the more likely they are to damage your car.
The first step in removing sap is to give the car a proper wash. Once that’s done, we recommend two methods to get rid of the sticky stuff: a homemade 50/50 isopropyl alcohol solution and/or a product specifically designed for bug, tar, and sap removal that you could buy at your local auto parts or big-box store. In addition to those, you’ll need some microfiber towels (try not to use harsh paper towels) and some gloves if you want to keep your hands clean.
Spray the sap and let the product soak in for a minute or two. Lightly agitate the sap—don’t scrub it in because the dirt in the sap could scratch your paint. Then use your microfiber in an upward-sweeping motion to lift the sap and dirt off. Spray the product again, let it sit, then wipe off more. Repeat this process until it’s completely gone.
Once your car is clean, you’ll want to protect it. If you want to go all-out, get a physical protective covering. If that’s too much trouble, you could also opt for a clear-bra-type protectant. Otherwise, you could simply wax your car or apply a ceramic coating to protect the paint. Any of these methods should help keep your car in better shape.
We appreciate your concern for your car’s health and hope that helps!