I am obviously missing something here, if the insurance company has written the car off, is it not the insurance companies responsibility to either replace the car or stump up the cash?
How does the BMW conversation fit in with this, where they going to give you a car on top of the insurance companies compensation, so that you effectively were compensated twice?
Lets make this simple.
if you think that the value of a 2008 M5 with X,000 miles on it has one value, and there is universal and unwavering agreement as to the value, then your perspective is not in line with the rest of the world. Why don't you stop posting about "didn't this get settled" and "hasn't insurance already handled this", as these simply seek to argue with others and not address any issue pertinent to the OPs case.
The value of a loss- NOT THE VALUE OF THE CAR- is something that may take quite some time to establish. In this case, the dealer's willful negligence has created a larger issue. An accident is one thing, a loss of the OPs car due to their willfull and reckless failure to protect his property and manage their employees is the issue.
My guess- and this is just a guess- was that the OP was going to take the insurance settlement of 'book value' and BMWNA was going to tack on some 'goodwill', and put him into a 2010 with 2600 miles...an imminently fair solution.
PLEASE do not whinge about double dipping or how the OP is seeking to exploit a situation to obtain 'betterment'.
OP, sorry to hear. Hopefully there is some 'papertrail' somewhere....