Who is trying to settle with you? If it is the other fellow's insurance company, I would tell them you want to pick out a top quality version of your car and have them pay to buy it. If it is your carrier, I would determine if what they are offering you (?) is all you want to spend.
Car's are relatively underpriced right now and gas costs have people worried. How many miles do you plan to drive per year and how much money over the settlement to you want to go, either out of pocket or by financing.
Wrong, no insurance company is legally liable to buy a car. They only owe the actual cash value of the car. That is an objective valuation.