I found a gel-like stuff (very sticky), and I guess it's tree sap, on my car. I was lazy and didn't clean it up until 2 weeks later. Now after I cleaned it with hand sanitizer and cotton, I see that the gel-like thing is removed but left an obvious spot on my car.

Does anyone know how can I fix it? It's a brand new car less than a month so I am trying to figure what actually it is and what can I do to fix it.

Any suggest appreciated!

 

If you run a fingernail over the surface, can you feel an edge? If so, the sap has eaten through the clear coat and partially through the paint. A lot of substances (including egg yolks) will do this, especially if left without cleaning for an extended period of time.

I once saw the paint on an Oldsmobile removed down to the primer by a fast-food type milk shake.

If no edge can be felt with the fingernail test, then it is likely a stain, either way: Check with a (more than one) reputable auto paint shop for an repair estimate... or perhaps contact the dealership about a repair under warranty