Australian cities have seen continued growth in private car travel that has imposed increasing vehicle energy consumption and greenhouse gas emissions. While much research has shown that travel demand is related to urban spatial structure, very little research has investigated the association of vehicle fleet fuel efficiency (VFE) and socioeconomic circumstance in urban areas. In this paper, we apply a Geographically Weighted Regression to explore intra-urban trends in socio-economic adoption of high efficient private vehicle using the case studies of Brisbane and Sydney, Australia. Specific attention is given to 1) what are the areas associated with high and low levels of VFE; and 2) how the VFE is associated with socio-economic variables (for example, household income) at local area. The identified spatial associations are then compared between Brisbane and Sydney to examine some important differences in the types of factors that associated with VFE in both cities. We conclude by highlighting outcomes from this research that are of relevant to policy makers, including those charged with identifying high oil vulnerable communities, designing intervention strategies such as implementing social and financial programs to improve household vehicle efficiency.