Trainee teachers' ideas about links between vehicle emissions and global environmental issues were studied using a 'graphic' questionnaire. Most respondents understood that cars contribute to global warming; two thirds identified carbon dioxide as being responsible. Half thought that heat from car exhausts causes the greenhouse effect. Two thirds realised that cars contribute to Acid Rain, but the unorthodox idea that carbon dioxide was culpable was predominant. Two thirds of the students thought, erroneously, that cars damage the ozone layer. It is suggested that students' thinking is over-generalised, and that misinterpretation of diagrams, errors in logic and non-specific language may contribute to their misperceptions. There is a possibility that misconceptions about this issue will be perpetuated in the classroom. Although there may not be room in students' curricula for more teaching about environmental issues, the environmental impact of cars could provide metaphors to illustrate general principles of learning and teaching.