low-speed, high load, MIVEC ensures optimal torque delivery with the intake valve closing timing advanced to ensure sufficient air volume. At the same time, the exhaust valve opening timing is retarded to provide a higher expansion ratio and improved efficiency. At idle, valve overlap is eliminated to stabilize combustion. Mitsubishi's 4N1 engine family is the world's first to feature a variable valve timing system applied to passenger car diesel engines. MIVEC-MD In the early years of developing its MIVEC technology, Mitsubishi also introduced a variant dubbed MIVEC-MD (Modulated Displacement), a form of variable displacement. Under a light throttle load, the intake and exhaust valves in two of the cylinders would remain closed, and the reduced pumping losses gave a claimed 10–20 percent improvement in fuel economy. Modulated Displacement was dropped around 1996. Current implementations Past implementations Footnotes Variable valve timing Mitsubishi Motors technologies