Electro-optical contrast ratio studies are made on polymer dispersed liquid crystal (PDLC) films with regard to automotive displays. Various methods of measuring and defining contrast ratio are compared and the dominating factors controlling each method are evaluated as related to PDLC displays. These methods are discussed in relation to the illumination technique used for display cells. Transmissive and reflective mode PDLC display test cells are measured with both black on white and white on black symbology. For evaluating direct view displays, contrast ratio measurements are made by using a TV/Video analyzer system. With transmission mode test cells, the contrast ratio is dependent upon the angle of illumination, and maximum values are observed with illumination angles in the range of 25-45° off normal, depending upon the PDLC film properties. Contrast ratio values from direct view lab models were in the 20-28 range for transmission mode displays and 10-26 for reflective displays. The use of colored filter segments in the reflective model resulted in similar contrast for all colors as for white. The lab models showed excellent viewability in bright ambient light, even direct sunlight, with increased brightness offsetting some decrease in contrast ratio.