If you bought the car brand new, you might consider sanding it slightly, applying primer, then painting it in the color it came with. They also carry Duplicolor, if you didn't buy it brand new. I was fixing an old Model T Ford radiator frame few years ago and got bored with it. That Model T was heavily pitted, and I started really smoothing it out. Shouldn't be too much different. You'll need primer that's specifically made for cars. 

I agree with @justin-shepherd

One thing I will add, make sure the primer is made for plastic. Plastic is harder for paint to stick to, that is why you often see it falling off of plastic parts on cars.

With a little duplicolor paint, it should match up enough to not be easily noticeable on a 6 year old car. I use the paint pens on my cars every six months or so, to just touch up any nicks from rocks and such.

rattle cans

Scotty advises

https://youtu.be/EEQmqRKqIsM?t=523