Scars do fade with time - the more serious they are, the longer it takes, and most take years.
My Husband caught his arm on a hot exhaust several years ago and the mark is still very plain to see (about 4 inches long)
I have heard of a product called BIO OIL that is advertised to reduced Scars, etc
http://www.bio-oil-direct.co.uk/
I have not used it personally, so can't comment first hand, however a cook i know says she is beginning to see a result, after a couple of months of use.