University of California Transportation Center

Since the 1970s, significant majorities of Americans say they support protecting the natural environment, even if it involves some economic cost. Yet almost every year since the 1970s Americans have driven farther than the year before, owned more vehicles, used them for a larger percentage of all trips, and shared them with other passengers less often. Vehicles today are much cleaner and more fuel efficient than in the recent past, but many of the potential environmental benefits are offset by higher consumption. This dissertation explores this apparent contradiction by analyzing the relations between environmental knowledge, environmental attitudes, and vehicle ownership and use. The research relies on quantitative analysis of responses from 1,506 Sacramento, California area residents to a 37-question knowledge-attitudes-behavior survey (39.6% response rate). Hypotheses were tested concerning the bi-directional effects of environmental knowledge and environmental attitudes on each other and on number of household vehicles, fuel efficiency of household vehicles, estimated annual household miles driven, and estimated annual household fuel consumption.

Difference of means analyses, multiple regression equations, and structuralequation modeling reveal that 1) respondents with pro-environmental attitudes know more about the environmental impacts of vehicle ownership and use, 2) the households of knowledgeable respondents own more fuel efficient vehicles and use less fuel, 3) the households of pro-environment respondents own fewer and more fuel efficient vehicles, drive them less, and consume less fuel, 4) vehicle ownership and use inversely affect environmental attitudes, but to a lesser extent than attitudes affect vehicle ownership and use, and 5) many respondents perceive constraints to making their vehicle ownership and use reflect their knowledge and attitudes.

These findings suggest that public education and social marketing campaigns focusing on the majority of Americans with pro-environmental attitudes, combined with policies to reduce barriers to less resource-intensive vehicle ownership and use, could encourage greater demand for more fuel efficient vehicles and lower levels of vehicle ownership and miles driven. They also highlight the research importance of effective survey design, appropriate measurement of latent variables, and the inclusion of

knowledge and attitudinal variables in some travel and environmental behavior studies.