How do insurance adjusters determine value of a car if it's totaled in an accident?
Actual cash value (fair market value) based on the sales price of like cars in like condition in your area at the time of the accident.
The insurance company will pay the "Fair Market Value" of your wrecked car. This is typically somewhere near what you would get from a dealer if you were to trade it in on a newer car. Closer to wholesale. If you still owe money to a bank or finance company, THEY get paid first, and you get what's left over.
Private Party value. Probably the midpoint. Around $8500. if your $7k & 10k figures are correct. You don't have to pay retail from a dealer and should not. I've never known anyone who was happy with what they were offered.
Your settlement for a total loss should be the average value. That's closer to the common sale price.
They use a replacement value, the money you would need to get another same year, make and model car. It is usually closer to the wholesale value. It can be lower or higher. The advertised value? Good luck with that.
They usually go by the blue book value, adjusted to local market conditions. So if in your area cars generally are marked up higher you would get that much more than blue book.
The same way you would if you were going to buy that car. They look up the NADA values, Craigslist, Autotrader, local ads, and calling around to dealers to find out what value they have for a similar car. Few people are satisfied with the offer. You can do any or all of the above and if you can show and prove a higher value than offered they most likely will accept that. Insurance companies live and die by documentation, so you need to do your due diligence. Also depends on which insurer is handling and paying the claim. Your own company is easier to deal with as they and you are parties to the same contract. If the other company is paying, your negotiating skills and documentation will have a lot to do with the settlement amounts. Had a motorcycle totaled out from under me. I researched what I thought the value was and when I went in to close the claim was offered a higher amount. Took it. They also reimbursed me for the sales tax which I was not expecting, but I was dealing with my own insurer.