Go to your local hobby shop with one of the cars, look at the Badger acrylic paints, I think you will find one very close. You can do a touch up of a scratch with a toothpick or a very small brush. Practice maybe on the end of the car where it is not very visible first. You will also find clear coats, flat, satin, or semi-gloss, that will match the gloss rather well.
Ray