In this paper we estimate a flexible demand system for private transport with data from the Encuesta Continua de Presupuestos Familiares. The usual pro-blem of zero records caused by infrequency of purchase is solved by exploi-ting the panel structure of this survey. The results show that carburants are demanded inelastically by all types of households, but the price elasticity for households in rural areas is significantly greater in absolute value than that for the rest of households, which suggests the possibility of complementary fiscal policies for the universally applied excise dunes.

Keywords: environmental taxes, household panel data, private transport.