How To Write A Diminished Car Accident Letter . The written demand needs to contain the following information: 3) include an explanation of why the other party (accused) should be held legally responsible for the damage and injuries caused. Car Accident Car Accident Letter from caraccidenttodo.blogspot.com Tell your friend or loved one, “you look like a million bucks.”. Document the amount of your lost value by ordering your diminished value report. (get the basics on writing a car accident settlement demand letter.).