First, I am an insurance agent for PA and laws do vary from state to state so your best option is to check with your insurance agent.
Your insurance policy does not come into play as you were rear ended, unless there is not enough coverage on the other veh's insurance to cover your loss. Your insurance may need to subrogate to get the money they pay back, but you're out of it at that point.
Your best option is to work with the company of the other vehicle and let them offer, then if you don't agree, or it's way less than the agreed value on your policy, you contact your agent and let them deal with it.
If you've not kept the value up on your current policy, or you only covered it for the amount you paid for it, that may be all you will get.
There is no advice like that of your agent in your state of residence. They are the person you should be directing your query to.
Kim(Alan's wife)