The dealership was referring to the state sales tax and the license plate; the bill you received from the County Auditor is for the personal property tax due on the vehicle. Taxes are due 120 days from the purchase date.
If you do not pay the taxes due by the due date, a notice will be sent to the Department of Motor Vehicles to suspend your driver’s license. If your driver’s license is suspended for non-payment of property taxes and you also hold a Commercial Driver’s License (CDL), it will also be affected by the suspension.
If you receive a property tax bill and you no longer own the vehicle, contact the Auditor’s office immediately concerning a possible proration of taxes owed.