This paper will present results from two sources; questionnaires conducted among drivers equipped with route guidance as part of the Berlin LISB trial and analysis of decisions made by users of the interactive route guidance simulator known as IGOR.The results from Berlin show a high level of commitment by participants in the trial but nevertheless show a general reduction in usage of the equipment over time. Adherence to advice is not high on regular journeys and reflects a low opinion of the quality of routes recommended by the system for such journeys. For finding new destinations or travelling in unfamiliar areas, opinions and usage are much higher. Overall driver behaviour has not been much influenced by LISB. Our surveys provide useful information on drivers' reasons for ignoring advice and their suggestions for system enhancement.The IGOR results provide strong quantitative evidence that acceptance of an item of advice is closely correlated with objective measures of its quality. It is also a function of the drivers' familiarity with the network, his previous experience of the reliability of advice and the degree of corroboration of advice by “external” evidence such as the orientation of the advice route relative to the destination, the absence of congestion and the behaviour of other drivers.