Whenever the board of county commissioners deems it necessary to purchase or lease motor vehicles for its use, or for the use of any department, commission, board, office, or agency under its direct supervision, or for the use of any elected county official or his employees, it shall adopt a resolution setting forth the necessity for such purchase or lease, together with a statement of the kind and number of vehicles required and the estimated cost of purchasing or leasing each. Upon adoption of the resolution the board may purchase or lease such vehicles, subject to sections 307.86 to 307.92 of the Revised Code.