This paper examines the capacity of suburban households to respond to a changing global energy context by changing their motor vehicle technology. Transforming transport systems will comprise a crucial element in policy and planning responses to energy and climate challenges. Government policy appears focused on a transition to more efficient vehicle types or alternative fuel and engine types. Yet such policies have failed to account for the considerable social differences in household exposure to the costs of transport energy constrain and the adaptability of households in altering their use of modes and vehicle types. Nor do such policies recognise how urban social structure, household social status and automobile types intersect spatially within Australian cities. This paper examines the links between urban social structure and the composition of the motor vehicle fleet to test whether the households that are most reliant on motor vehicles for transport have the financial capacity to rapidly alter their vehicle technology in response to changing energy price and supply conditions. The paper uses ABS Census data and motor vehicle registration data at the postcode level to compare socio-economic status with the age, fuel consumption and value of the suburban vehicle fleet for Brisbane and the Gold Coast. This spatial deployment of Census and vehicle registration data is novel in the Australian context. The paper argues that policies that focus on vehicle technology alone face a number of social equity hurdles as measures to overcome urban transport fuel security problems.