This sucks so much but you can definitely make the insurance company do much better. When my high-mileage (164k) e46 was totaled (2000 328i, obviously not a ZHP) they initially offered $4,300, which I thought was way too low, but I sent them other listings of manual transmission cars in the same condition and argued some things. I emphasized how much work had gone into keeping the car in top shape (with receipts for parts & shop work) & the impossibility of finding an equivalent for sale that didn't need thousands of dollars of major repairs. People on e46fanatics pretty much uniformly told me that wouldn't work, but the insurance co. changed their offer to $7000.
So like everyone else on this thread who's been through it before, I'd just say to politely keep pushing and give them all of the info you can, and they'll be willing to work with you. I'm sorry this happened to you but glad you were ok!