My wife was backing the Jeep out yesterday and rubbed the right rear tire on the left rear quarter of the car (realizing it, fortunately, before she did any further damage), resulting in some real nice streaks and rubber marks around the wheel well

The bug & tar remover has helped somewhat...it's requiring a substantial amount of elbow grease but it's slowly getting some of it out. There are still some faintly visible thin black streaks that clay is not taking out. Has anyone had to remove this kind of material from the paint and if so, what did you use? We're not talking the good kind of

rubber in small flecks, either...more of a smudge mark that won't scratch off with, say a fingernail. Any suggestions are appreciated. Thanks.