Original 1938 Oldsmobile Motor-Graph book that provided a scientific, copyrighted system for determining the most economical time to purchase a newer car.  The graph is set up to compare cars from 1934, 1935, 1936, and 1937. There are approximately 24 pages for the analysis with a cabon copy (one for the dealership and one for the customer). Includes the carbon paper. Pages are perforated for ease of tearing out-of-book. Very neat and unique piece. Outside covers are slightly soiled.