I doubt that it was a fake one. Maybe not a completely finished one, but it was at least working as a car since they broke a record for that stunt if I remember well.
Also note that even for non-crash scenes they damage cars: I have read that one (or some?) db5 were damaged in the chase scene between the db5 and a Ferrari in one of the JB movies of the 90s, I do not remember which one.