If your in an accident that wasn't your fault, your going to have to get your car repaired, deal with the repair shop and for the most part your life is going to be completely disrupted and unless you were injured, you most likely will not be compensated at all. You will have an uneasy feeling that you are loosing something in the deal, but you just don't know what it is or what it's called.
Your vehicle even if properly repaired is now worth less than a similar car that has not been in an accident. How in the heck do you prove that it will be worth less without selling your car? Well it's called Diminished Value and you won't find your insurance comany volunteering to tell you about it. In nearly every state the victim of an automobile accident may be able to pursue a claim for diminished value against a third party/third party insurer.
The factors that usually dictate whether there is a diminished value on the vehicle and how much that loss will be include the age of the vehicle, its condition before the accident, prior accidents, the mileage, the extent of the damage done in the questioned accident, the value of the vehicle undamaged and the overall demand for the vehicle in the marketplace.
A general rule of thumb for vehicles that are 2001 model or newer with no prior damage and with at least several thousand dollars worth of repairs is that the vehicle loses in the range of 10-25% of its pre-loss value. You will need to get a Diminished Value Auto Appraisal Report to know how much and to file a claim.