Scratches, bird droppings, tars, etc are among the toughest stain to remove from car paint. However there are probably possible to remove using expensive commercially made wax polish which you may think twice to buy. Another way is sending it to car wash but they won't be able to clean them properly or you have to pay more money for them to do the job.
In this video shows how we can use 80 cents powder to remove any of the toughest stain almost anything and sometimes maybe including minor rust. Beside being cheap and effective it also environmental friendly - indirectly edible powder.