A claim must be opened up with a claim demand letter and proof of loss which is a diminished value appraisal. It is a process of time, negotiation and supplemental proof. The most common claim being inherent diminished value, which is when a car is repaired and left with a bad history report creating an attitude of distrust towards the quality of the car since it has suffered a traumatic event.
A claim can also be opened before repairs which is called immediate diminished value, meaning the car is not repaired but has a loss that will occur even after repairs. The calculation for immediate diminished value is repairs plus the diminished value not exceeding the actual sales price of the vehicle.
Repair related diminished value is when the body shop does bad repairs which leave the car in a worse condition than it was prior to the accident or when the insurance company forces recycled, used parts and or non-oem parts to save money which happens in most cases on top of filler repairs so the car history will not say frame damage if it were repaired correctly.
For example: In some instances when there is Quarter panel damage that must be cut the insurance company will order frame pulling and filler and not cutting which affects repairs and stability of the car but keeps the car off the frame damage list. This is why an expert must do the diminished value appraisal report in order to assure that the repairs were done to industry safety compliance standards.