Scratches or chips? Also, what color is the car?
There was a chip in my girlfriend's bumper right near the wheel well on her 09 Super Black hatchback and I filled it in with bondo primer/putty (
http://ecx.images-amazon.com/images/I/3 ... AA280_.jpg). After I let dry, approximately one hour, I then took a very fine grit sand paper and made sure the job looked clean. After that, use the aftermarket Nissan Super Black Paint repair tube/pen. This is something you can get from your dealer, all colors are available...if not, anything Duplicolor like this (
http://www.drillspot.com/pimages/2808/280873_300.jpg) will work. Afterwards, look for a Duplicolor clear coat to put on over the chip to give it that shiny look/feel.
Note: I did this to her BLACK Versa. Last time I did this to a white car (Nissan Skyline) it ended up looking pretty crappy. Black is just so easy to fix. I imagine anything but white/blue/silver would be easy to match. Good luck with the fix, hope this helps!