S.C. Code Ann. § 12-37-2640

The auditor shall determine the assessed value of the motor vehicle and shall calculate the amount of taxes on the vehicle. However, in the case of motor vehicles whose model year is fifteen years or more prior to the tax year, the assessed value is fifty dollars and in the case of a motor vehicle whose model year is less than fifteen years prior to the tax year, the assessed value must not be less than fifty dollars. The millage to be applied to motor vehicles licensed during January through December of each year must be that applied to other taxable property within the county, school district, special or tax district and, if applicable, the municipality for the preceding regular tax year.