In this paper, we analyse the opinions, attitudes and willingness of consumers to pay for biodiesel as an alternative to diesel in Barcelona province. Data were gathered from face-to-face structured questionnaires from 300 diesel car owners/users that regularly purchase fuel. A variation of the traditional choice experiments (CE) was used by excluding the price attribute from the design. In a subsequent contingent valuation (CV) exercise, respondents were asked to state their maximum willingness to pay (WTP) for their preferred choice sets using the