The purpose of the auto Insurance is to pay the damage of the vehicle insured or third party damage should an accident happened.

First we must determine who is the owner of the vehicle, if the vehicle is still under finance leasing, then you will not have a say on how much to insured for your vehicle as the finance company is rightfully the owner of the vehicle.

If a car is till under finance leasing, you have to go for comprehensive insurance where it cover all the parties involve in the accident.  The sum of insured is usually the market value of the vehicle.  Finance company usually has a guide line to determine the market value of the car.

You do have the option to purchase option insurance such as windshield insurance, natural disaster insurance etc.

If your car is not under the finance leasing anymore, then you can determine the amount that you want to insure.  For example your car value is $15,000, you may insure it for only $6,000 if you think the amount is sufficient for you to repair your car should an accident occurred.  Please take note that the sum of insured is the maximum payout from the insurance company should you make a claim if an accident occurred.