So, . . . . what happens when the insurance company (not yours) gets tired of dealing with you and inspects your vehicle VERY CLOSELY, then decides that its overall condition (and value) should be downgraded because of other wear/damage/corrosion/mechanical conditions? (which they found) IMO, there are NO two identical used vehicles, only similar vehicles.
How much money are we talking about here? Attorneys typically charge about $500/hr for this type of work. What's your time worth? Sometimes its best to just (over) state your initial settlement price, then negotiate to the mean, . . . . . . and move on.
IME, the more you want to play hardball with an insurance company, the more they play hardball with you. They already have all the attorneys they need, . . . . . on staff, and, they know the law in your jurisdiction. Do you?
Chum lee