Driver interfaces for electric vehicles

The dissemination of electric vehicles (EVs) is an important step towards a more sustainable transport system, but barriers to adoption persist. Much effort and resources are put into solving battery technology related issues and progress is made continuously. There remain however important matters that have not been equally discussed; the design of user interfaces and human-machine interaction (HMI) of EVs is one. This paper seeks to examine a few of the issues regarding EV HMI through a study that evaluates two different concepts for an EV instrument cluster in order to develop knowledge on (i) what information is relevant to present to the driver of an EV and (ii) how that information should be presented; innovatively or in a more familiar way. Two consecutive user tests, according to a between-subject procedure, were used to test two concepts in a driving simulator. Ten participants, with little or no experience of driving an electric or a hybrid electric vehicle, tested each concept. The participants were asked to drive the EV simulator and to interact with the user interface while different events were triggered, designed so that the participants would experience several of the situations that might appear when driving an EV for a longer period of time. Data was gathered through objective measurements, e.g. time, number if errors etc., as well as through questionnaires and interviews The results show that participants had problems understanding the EV specific information content independent of concepts, even though they considered the information shown to be the right one. Both concepts had advantages and disadvantages, most notably that participants expected the vehicle to work like a conventional car when the interface was traditional and that they felt insecure when the interface was innovative. Some of the discovered problems can be attributed to the participants' lack of knowledge and useful mental concepts regarding electricity and batteries, which made understanding the information difficult. More research on how to support EV drivers through design of the HMI given these deficiencies is needed.