Tony,
I'd strip the add-ons anyway if they are going to total it - insurance companies will give you absolutely nothing for add-ons in most cases. Just don't tell them about it and put the original parts back on. As far as their offer - I'd tell them you want more & get some ammo to back up your contention that the vehicle is worth more. They are going by a used car guide which, in many cases can be WAY off base. The fact that your car had extremely low miles makes the book even further off. Anyway - gather your ammo - go to as many resources as you can find with similar VX's with low miles (this site, autotrader.com, carmax web site, etc) and print out the descriptions and prices, then get ready to fight!! Good Luck!