Things you added and things you did to the car mean nothing when you're talking to an insurance adjuster. They are going off the year and model of the vehicle, nothing more.

If you haven't filed a formal claim yet, cancel it. If you've filed a formal claim, you're kind of SOL. You can either allow them to total it and take the money, or you can buy it back from them as a "salvage" and have it rebuilt at your expense. Be aware that doing this will mar the vehicle's value forever since it will carry a "salvage" or "rebuilt" title. Depending on your state laws, the vehicle may not be allowed on the road until it has been rebuilt and inspected to insure roadworthiness.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)