A secondary task measure was used to evaluate the effects of various automobile handling characteristics on driver workload. The study was performed using the VPI & SU driving simulator, a variable speed random number generator and display, plus other control and recording equipment. Workload scores for 82 subjects were determined under various combinations of wind and curvature disturbances, vehicle steering gain, and vehicle response time. Driving performance was analyzed to measure intrusiveness of the secondary task and to confirm workload differences. The results showed definite differences across the levels of combined wind and curvature. These supported the assumption that the secondary task measure would be capable of measuring differences in driver workload. No significant differences in workload scores were obtained for changes in steering gain or vehicle response time. The secondary task did intrude on the primary task, indicating that its use may cause experimental complications. The method and equipment appear to be useable in either simulator or on-the-road vehicles.