+1
Very, Very unlikely to be a cat, they simply don't have the strength or weight to scratch down to the metal and even if they did they can't just open one claw at a time so there would be some evidence of light parallel scratching. Seeing as your car is black there would also be very obvious footprints as well, I can always tell when one's been on my car .
Pete
I would agree Pete from my experience of the little frickers