Why doesn't the insurance company pay off the whole amount owed in car?

If the automobile insurer for the at-fault party is paying your claim in the first place, it means that they are acknowledging at least partial liability for this claim.  However, if your vehicle has been deemed a total loss, they are only responsible for the "Fair Market Value" (FMV) of your vehicle as of the date of loss.  There are certain vehicle comparison tools that may be utilized in determining FMV, but by and large, the offer should correspond roughly to the FMV according to the NADA Guides.   Remember: The law related to property damage claims such as this only holds an at-fault party responsible for fair market value at the time of the loss-- not the market value when the vehicle was manufactured, not what you purchased it for, and not what you may owe on the vehicle.  Also, if there is a plausible argument that you were at least partially responsible for the wreck, the offer you receive from the insurance company may reflect that.  That is, there may be a downward adjustment from fair market value for the percentage you could be found to have been partially at fault.  I am in no way assuming that is the case, as I do not know the facts of your incident, but I do know that is a factor that plays into insurance companies' valuations.   My best advice for you is to ask the claims adjuster what factors his or her company analyzed in arriving at the offer.  Ask for the insurer to send you a copy of any appraisal or market report that was prepared prior to the communication of the offer.   Good luck, Lance R. Ladendorf, Esq.