High Quality Content by WIKIPEDIA articles! Pac-Car II is the world's most fuel-economic vehicle. It was developed as a student project at ETH Zürich (Swiss Federal Institute of Technology). Based on a group of students and an experienced teamleader, the goal was to build a vehicle that uses as little fuel as possible. By using hydrogen fuel-cell, developed at ETH/PSI (Paul Scherrer Institute), as power source, pure water is the car's only emission. Clean mobility completed therefore the educational and energy saving aspects of the project.