When is a car no longer “original”?

I'm sure this has been argued many times but I tried finding more information about general opinions and failed to. When is a car no longer original? Many folks have bits and pieces restored on their vehicles and I imagine it can get to a point where their "original survivor" is really a restoration. I'm in strong favor of NOT restoring a good, original car but the temptation to make them look better is sometimes irresistible. I myself have a car I'd like to get the bumpers rechromed on....

When is a car no longer "original"?
Author: challenger