Agreed value is an agreement between the customer and insurer on the value of a car at the time of taking out the insurance. This figure then remains fixed for the duration of the policy. This means that, should a claim occur, you will be covered for the full cost of the originally agreed value rather than the current market value of your car. For classic car insurance, agreed value can be useful as it prevents your policy from paying out less should the market value of your car diminish over time.