The first question is what caused the black marks?
Rubber tires leaned agains or piled on the car? Usually a carefull rub down with a cleaner like Acrosol or brake clean wil take that of. CAUTION these chemicals can damage some paints, BE gentle.
Tree sap, good car wash soap will clean this.
Etching in the paint because moss has grown in the cracks and cranies. Good soap followed by a light cut polish will make for the best result.
black
A sandblaster or sanding disc
A person can remove greasy hand prints from a car by washing it. If they do not come off after a car wash, then a wax may be needed.
Warm soapy water and a sponge.
use wd-40 works great for tar also
spit in your car
Dot 3 Brake Fluid
Exterior means "outside". For example, The exterior of the car is red. Meaning, the outside of the car is red.
painting it over black
take it to a good body shop with a qualified tech!
spray WD-40 on the marks and they will come off not affecting the paint!
The paint is on the exterior of the car.(example) I just painted the exterior of my house to raise its value