Information modalities and timing of ecological driving support advices

Within this study the outcomes of two driving simulator studies are reported. In the first study, three different human-machine-interaction modalities for an ecological driving support system were compared concerning driving behaviour, workload and user acceptance parameters in order to find out whether a haptic acceleration/deceleration and gear shifting advice improved the ecological driving style additionally to a visual feedback system. Results showed that the combination of the visual and haptic modality led to the fastest reaction times and smallest deviations from the optimal acceleration and gear-shift behaviour. Yet, the results of the acceptance questionnaires revealed that the participants preferred the visual display, whereas the haptic feedback showed the best results regarding the workload scores. The second study dealt with the timing of the feedback. When should ecological coasting advices be presented in order to reach a high-user acceptance? As an outcome, the participants decelerated earlier receiving a coasting advice. However, if the advice was given too early the acceptance of the participants was low.