A Volkswagen research team compared a 3-cylinder diesel engine with either a turbocharger or a Comprex supercharger in an effort to improve fuel efficiency and meet future emissions standards. They combined direct fuel injection, an electronic injection pump, and the supercharging systems to enhance performance. The 3-cylinder design saves space and weight, while direct injection boosts fuel economy by around 15%. The electronic injection pump allows for precise adjustments, such as timing and full-load behavior. Both the turbocharger and the Comprex supercharger showed promise in increasing power and torque while improving fuel efficiency. Tests on engine test beds and real roads provided data supporting these advancements, suggesting potential for even further development.