Earlier studies have shown that drivers' visual scan patterns and dwell times are changed when using an in-car navigation display system. The fact that these changes occur raises questions about the driver's ability to adapt appropriately to high-demand driving situations. Thus, additional experiments were conducted to determine whether or not drivers adapt appropriately to high driving task demands while simultaneously navigating. One experiment was designed to investigate adaptation to high anticipated driving task demand and a second was designed to investigate adaptation to high unanticipated driving task demand. The results of the two experiments demonstrate clearly that as driving task demands increase, drivers do indeed shift their visual sampling strategy appropriately. However, variability in the data suggests that good human factors design and appropriate placement of the display remain important issues.