UC Davis Institute of Transportation Studies

In this paper we seek to document what, if any, divergences exist between how experts and ‘lay’ people conceptualize the energy used in automobiles, motivated by previously-documented divergences in the home energy sector. From a total of 15 interviews with 19 individuals, we identify several common ways ‘lay’ people think about automobile energy use, and draw a number of conclusions relevant to the development of transportation energy policy. In our informants’ minds, automobiles use gasoline, rather than a more generic form of energy, and they therefore have a difficult time comparing energy use across activities. When asked to compare their total energy use for both residential and transportation activities, informants used dollars to provide a common unit of measurement. Our informants thought of automobile efficiency almost exclusively as fuel economy and were aware of it, albeit based on inconsistent methods and varying degrees of rigor. They measure fuel economy almost exclusively in miles per gallon and demonstrated easy familiarity with this measure—they were very comfortable comparing their present cars with past cars, or with other cars in terms of fuel economy. However, the prevalence of this volumetric, more-is-better measure may present challenges for communication as alternative fuels (e.g. electricity) gain market share because such fuels may not comport with this measure in an intuitive way. In-dash fuel economy displays seem to have made some drivers more aware that driving behavior is a factor in realized fuel economy, although it appears that this link could be strengthened if displays were to provide more pertinent information. However, in contrast to home energy use where active management is a primary means of saving energy, automobile energy use is considered primarily at the point of purchase rather than in daily driving decisions. Finally, our informants tended to evaluate their fuel economy relative to a benchmark of some kind, whether CAFE standards or their perception of the fleet (or vehicle class) average.