Birds attacked my car last week. I was driving on the highway under an over pass and I heard some light thuds on the top of my car, I didn't think anything of it till I got out of my car and Saw 8-10 bird shit drops in a row starting from the top of my car down to my spoiler. I waited too long before taking it off. And I can still see the outline of the droppings on my car especially on my spoiler. I've tried using everything I had to clean it off. Any suggestions before I resort to gasoline.