Yes, good question, Tony. Like the Viking axe that has the handle replaced at some time. Is it still original? And then the head of the axe is replaced a little later on. These are interesting and philosophical questions. Maybe it goes to the passage of time. For example if the original handle of the axe was replaced 100 years into the Viking period (meaning that the entire axe is still about 900 years old instead of 1,000), then would a historian still consider it an original axe? Maybe the answer is yes, but if the handle was replaced yesterday then it's not so original. There is no doubt that the hero car has a higher provenance. My understanding is the wrecking yard number two car did all the heavy lifting but is essentially a "turtle in a half shell."
Maybe 500 years from now our future society might revere the number 2 car just as much as the number one because it was redone so close to the period of time of the manufacture of both cars.
As an addendum, I have heard of Cobras where the only original part left is a door handle or a door hinge. Hmmmm.
Wonder how Socrates or Nietzsche would approach the subject.