What the car is “worth” has more to do with the cost of replacement than anything else. This is a lot like why you have your wedding ring appraised for insurance purposes. You couldn’t pawn a $3,000 diamond ring for more than $300 but if it was stolen it would cost you $3,000 to replace it.
The other insurance company declared your car a total loss so that they can avoid repairing the car. It would probably cost a lot more than the value of the car to repair it. That doesn’t make any of that your problem.
In insurance terms, replacement means the cost of replacing the item via the retail market: the price the item sells at retail in your area, given it’s pre-accident condition. The best thing to do is to find out what your car would have sold for retail if it was sitting on a used-car lot. Chances are that the cost of replacing your exact car (hypothetical) on a used-car lot is much higher than what you will be offered to settle this accident.
Go online and find as close a match as you can to your car’s make, model, condition and mileage and options in your area. See what the asking price is for very close matches.
That’s the amount you want to settle for, unless, by the way, if you were in ANY way injured.
If you were injured, then you are entitled to compensation for any medical costs and may be able to win compensation for pain and suffering, loss of income, etc. In this case you probably need a personal injury lawyer.
If you were completely unscathed then just make sure you don’t settle for damages less than your loss. In this case, you should at least be able to be in the same car: year, model, year and mileage at zero cost to you.