(a) For the year 1981 and thereafter, the department of revenue shall annually adopt a schedule for determining the value of all motor vehicles, the model year of which is 1981 or thereafter, as of the time they are first offered for sale as new motor vehicles. Such schedule shall be adopted as a part of the rules and regulations adopted by the secretary of revenue for such purpose. Such schedule shall show the classification of all such motor vehicles in accordance with K.S.A. 79-5104 based upon the value so determined. In formulating such schedule, the secretary may use the trade-in value for each particular make and model as developed from national market reports or other similar, nationally recognized publications. In the event the secretary of revenue is unable to ascertain a value by this method in respect to any motor vehicle by reason of the same being a specifically constructed motor vehicle, or for any other reason, the county appraiser shall determine, from any information available, a comparable value of such vehicle pursuant to rules and regulations adopted by the secretary of revenue for such purpose.