Manufacturers of large engines and their components must pay greater attention to legal requirements for reducing pollutants. Even off-highway engines are being put to the test to ensure that they meet the required exhaust gas quality in every performance range and reduce fuel consumption. The International MTZ Symposium “Heavy-Duty Engines” takes a practical approach to system optimization and component development for these power units. The conference also highlights the progress made by engine manufacturers in the development of on-highway engines, among other things, to optimize drive systems in terms of fuel consumption and emissions.