This study aims at understanding how a general positive attitude toward the environment results in a limited purchase of environmentally friendlier cars, often referred to as the attitude-action gap. In a first experiment 27 volunteers performed a judgment task on car purchase intention. Participants were asked to evaluate the probability of buying cars varying in purchase price, environmental performance, operating cost and vehicle quality. A second experiment required 47 participants to express their purchase intention of vehicles varying in driving experience, environmental aspects, Life-Cycle Costs and vehicle quality. Results in both experiments show that participants integrate car attribute information according to a differential weighting averaging rule. Model weight and scale values show to be indicative of a positive attitude toward environmental performance. On the other hand, the empirically established model weights consistently indicate that environmental performance is outweighed by other car attributes. Conceptually, the averaging integration model provides an explanation about the psychology of the attitude-action gap. Implications for policy making are discussed.