Seven navigational devices were tested in the Federal Highway Administration Highway Driving Simulator (HYSIM) for their effects on safe driving performance. Younger, middle-aged, and older drivers, 42 in each group, navigated a 26-mi (42-km) route through simulated streets of Detroit, Ml, using one of seven devices. A control group used strip maps. The other six used either an auditory or visual device which was of either low, medium, or high complexity. The difficulty of the driving task (workload) was increased in three successive sections by adding crosswinds, another vehicle, gauge-monitoring, and mental arithmetic problems, and by narrowing the lanes. Measures included speed, average and variance of lateral placement, heart rate, and reaction time to gauge changes. Results indicate an interaction of age group and level of difficulty, such that higher levels of difficulty affected older drivers to a greater extent. Device differences suggest that auditory devices are somewhat safer than visual devices, and moderate levels of complexity are preferable to higher levels. The complex visual device had the longest reaction times and the slowest speeds in sections where navigation tasks were performed.