My parents had a three year old Rambler that was totaled back in 1963. Fortunately, nobody was injured. They had just put new tires on the car and had replaced the battery. The car had 36,000 miles at the time. What my parents did was locate a similar car. This car had gone 45,000 miles and had two new tires. The insurance company negotiated a price with the dealer, gave my parents a check for the negotiated price plus an added mileage allowance and an allowance for two new tires and a battery. In this case, it was the insurance of the party that rear-ended the first Rambler that had to pay.
If this is your insurance company that is having to pay, I don’t know whether you could work out the same deal. However, I think I would look for a similar Altima, get the price from the dealer, add for recent work and see what happens. In my parents’ case, the insurance company gave them a check. They could have done anything they wanted with the money. They elected to purchase the replacement Rambler. Interestingly enough, the replacement had the same engine and transmission–had identical equipment and trim except for the color–but somehow seemed to run better and had better acceleration.
In your situation, try to negotiate for the best settlement you can get and let the insurance company have the car.