Reducing the fuel consumption of cars is seen as a central element in reducing CO2 production by individuals. The automotive industry currently focuses on more efficient engines and alternative power concepts. Our research complements this by an assessment of how drivers can reduce fuel consumption of their vehicle by changing their behavior. An initial study reveals that individuals have a poor understanding of the cost of driving. Looking at ubiquitous technologies we believe that there is a great potential for saving energy. Information can help to reduce the need for driving. We make concrete suggestions of how user interfaces in the car can make the user aware of the potential of reducing fuel consumption.