Highlights•We found two distinct types of drivers.•We find that prior efficiency strongly impacts feedback efficacy.•Some drivers are confused by feedback and this results in a lack of efficacy.•Technical proficiency with the vehicle is an important factor in efficacy of feedback.•We find an overall 4.4% improvement in efficiency due to feedback.•The magnitude of behavior change is correlated with changes in attitudes during the course of the experiment.

AbstractThis paper presents results from a study of driver feedback, driver attitudes, and the adoption of ecodriving behaviors. The study ran for one year; each driver was engaged in the experiment for four weeks. Narrowly defined, ecodriving represents the set of behaviors that a driver can use to minimize the energy use of a trip after the trip has begun. The general ecodriving behaviors are moderating acceleration, top speed, and braking. Ecodriving has long been recognized as a potential source of reductions in transportation energy use, with reduction estimates ranging widely from less than 5% to over 20% depending on context. In-vehicle feedback that provides drivers with salient information suited to their personal goals may be one way to motivate ecodriving. Although many studies have tested unique feedback designs, little research has been conducted into the cognitive precursors to driver behavior change that may underlie the adoption or rejection of ecodriving practices, and therefore underlie the effectiveness of any feedback design. This study examines both precursor cognitive factors and driver behavior changes with the introduction of energy feedback, using a framework hypothesizing that attitudes, social norms, perceived control, and goals influence behavior and behavior change. The study finds that the introduction of a feedback interface can both activate these cognitive factors and result in behavior change. Furthermore, the study finds that there was an overall 4.4% reduction in fuel consumption due entirely to one group that showed increases in their knowledge of fuel economy and reported high levels of technical proficiency during the experiment. Statistically significant relationships are found in this group between the magnitude of cognitive change and the magnitude of behavior change – supporting the theoretical framework. The second group made no improvement and may have been confused by the feedback. The effect of baseline (pre-feedback) performance of the drivers indicates drivers that already have highly efficient driving styles do not benefit much from feedback.