Smaller engines, producing the same power as the larger engines they have replaced while using less energy and therefore generating lower exhaust emissions, are high up the priority list of every vehicle manufacturer. In truth it is part of a process that has been continuing for many years. In this interview, Matthew Beecham talked with Derk Geurts about trends in diesel engine downsizing. Derk is Delphi's chief engineer for diesel common rail systems (light duty and passenger cars).