My friend Mike has been in the appraisal business for almost 40 years. He is a member of the advisory board for Hagerty, Hecock and several other ins. co. He also travels around the US to conduct appraisals and also is called to testify on behalf of owners of cars and or on the other side for the ins. co.
He says that unless you have an "Agreed Upon Value Policy", in the event of loss, you are 100% screwed. In fact, using your info above for example, you insure your car with State Farm on a regular type policy and they set your "Stated Value" at 10.5k. If you total that car and have a regular stated value policy and not an agreed upon value policy, all you will get from them in the event of a total loss is the $4500 book value you also mentioned above. You could have 10 appraisals all stating the ar is worth 20k, but if your policy is NOT "Agreed Upon Value", those appraisals are worthless.
I am only trying to help people out here, I see and hear this stuff daily from Mike as I spend my days at his house/shop/office. I have even traveled with him to conduct appraisals etc. and have seen this stuff first hand. Let's put it this way, this guy gets $250 per appraisal and that is if you bring the car to him. If he travels, he get's milage, time and the appraisal fee on top of everything else. This is a guy who knows this stuff inside and out.
He has shown me case files of people who have a collector car or classic that was worth a ton of money and for some crazy reason had these cars insured through regular ins. co., had a loss and then were given book value. As you can imagine, these people are devastated and beside themselves and there is nothing they could do.
I myself had a loss with my 68 Firebird this past Dec. I had the car insured through Hagerty and had no issues at all when I put a claim in for the damages. I had my agreed upon value set at 30k, damages came in at 15k. Had I actually had the car fixed, there would have been another 5-10k in supplamentals. However, I choose not to have the car repaired so I took the 15k in repairs and parted the car out for another 12k. I went this route because I knew the car would take a very long time to repair and I also wanted to keep my engine and trans.
Bottom line, shop wisely and research these policies inside and out because these cars do get hit and more than you might expect. Using our accident as an example, there were almost 20 cars stopped for an open draw bridge. Of the 20 stopped cars, Mike and I had the only two classics. Both were hit, his 65 Tempest was rear ended by me after I was rear ended by a lady going 45mph and never touched her brakes. 15k damage to our car, 5k to his, and up to this point over 40k in medical expenses.
So yes, this stuff does happen. And to think our accident was due to an "undocumented visitor" aka: ilegal alien. The only weird thing is, this "undocumented visitor" amazingly actually had insurence! Go figure that one... LOL