Investigating users' preferences for Low Emission Buses: Experiences from Europe's largest hydrogen bus fleet

•We investigate bus users' preferences for emission reduction in bus travel.•We conduct a Discrete Choice Experiment amongst Aberdeen bus users.•We make use of a natural experiment – the Aberdeen Hydrogen Bus Project – to examine the role of direct experience in preferences.•Bus users place a higher value in the reduction of local pollutants over greenhouse gas emissions.•Increasing experience using a hydrogen bus has an effect on preferences for the comfort and bus emissions attributes.