I think the Autosmart tardis stuff is a bit stronger than AG tar remover?
Personally i would get some tardis, Put kitchen roll soaked in tardis over each of the tar patches, And leave it to dissolve it, Then work with a claybar after youve got as much as you can off to remove the residue.
Make sure you give it a good coat of wax when you get it off to put some protection back on the paint.
Cnut whoever did it !