This project evaluated how driver interaction with an in-vehicle navigation system (IVNS) affects driving performance and safety. Researchers collected measures of simulated driving performance during interaction by 13 different subjects with an IVNS digital map display, using a Honda Acura placed within a fixed-base wrap-around driving simulator. Subjects (Ss) navigated along a maze-like route laid out within a simulated road grid. Dummy Global Positioning System (GPS) coordinates, corresponding to the position of the vehicle in the grid, were transmitted to the IVNS and updated continuously as vehicle position in the simulation environment changed. A digital map of the grid, with an icon representing vehicle representing vehicle position superimposed, was displayed on a laptop computer placed in the Acura. Under the control condition, Ss were not given turn instructions. Results indicate that for the test relative to the control condition: * Visual interaction with the IVNS display was greater and task completion times longer. * More variability in vehicle control was observed for measures of average vehicle speed, peak speed, percent braking time, peak braking pressure, and vehicle heading. Subjective responses from simulated driving and a separate group of on-road Ss identify both navigation benefits and possible safety problems with the system. It is a reasonable assumption that increased variability in driving performance elevates driving accident risk. Both the simulated driving and subjective response results, therefore, point to possible safety implications in IVNS use for the driving public. The findings suggest that as IVNS use becomes more widespread, both navigation benefits and possible adverse driving safety effects of such systems need to be considered.