This study has evaluated the effect of several formats of electronic/electro-optical display with emphasis on the speedometer. A total of 400 drivers has participated in laboratory and road trials. These latter were conducted both by day and night over a carefully selected route.Overall, the digital speedometers were read more accurately than circular and curvilinear analogue electronic displays or conventional instruments. The electronic instruments were generally well liked. The most frequent preference was for the digital speedometer, which was considered easy to read and to relate to speed limits. This preference seems strongest for drivers aged over fifty.