How do you get cigarette ash out of the roof of your car near the window?

[JohnGraber]

Its not a burn ts the ash. My wife smoked in my car and when going to throw the cig out the window she smashed it against the fabric of the roof so now there is a big black streak. I don't want to take a towel or rag to it because I'll just rub it in and or smear it making a larger black mark.