This study was conducted in an attempt to improve drowsiness detection in automobiles by examining velocity-related measures. These measures were also included in multiple regression-generated drowsiness detection algorithms to determine their contribution to detection accuracy. In addition, the effects of cruise control and an auditory secondary task on the level of drowsiness and driving performance were examined. Twelve volunteers from the Blacksburg, Virginia area were used as subjects. In the early morning hours after sleep deprivation, subjects drove a moving base automobile simulator, during which time physiological and performance measures were gathered. Data analysis revealed that velocity-related measures can be good indicators of drowsiness when subjects are without external stimulation, but otherwise, these measures are fairly weak indicators of drowsiness. Similarly, the addition of velocity-related measures to drowsiness detection algorithms proved to be quite modest. Finally, there was no significant main effect of either cruise control or secondary task on drowsiness or driving performance. / M.S.