Diminished Value or DV is the loss in value of your automobile due to an accident. Simply put, wrecked and repaired cars and trucks are worth less that ones without an accident history.
If the accident was not your fault, and the at fault driver can be identified, yes, they are required to pay the loss in value of your auto. This is in addition to the repair cost, and the loss of use.
Generally, repair severity will have the biggest effect on DV. Vehicles with SRS deployment, unibody, frame or structural damage are contributing factors. Market research indicates on average, 12-15% of its pre loss value for an accident, 22% if structurally damage and repaired. Your results may vary.