How do we value our cars?

I have a friend, decades ago that had a 57 2-door Chevy with a stated valve of 10,000 policy. Someone in a 260Z ran into the front fender and bent the upper control arm. The blue book valve at that time was for 600 dollars. They were going to total the car till he said "You mean that you are going to give me 10,000 dollars for a fender bender?" They said "what do you mean?" and he told them about his stated valve policy. The insurance company fixed it instead.
To prove the value of your repair, sometimes you have to show them(proof to them) what it would cost to replace it with the same condition car.
I truth what I have heard from some insurance company's is they will try to work with you. Lets wait and see, of course do your research now while waiting in case it turns sour.