Mitsubishi made an engine coded 4G12 I think it was the first to feature some form of variable displacement. (Modulated Displacement) technology,
I remember this from a magazine I read many years ago but I could never find it again.
Mitsubishi had a 4 cylinder engine that de-actived cylinders. I think it got something like 60MPG at 50MPH and had 115HP? I cannot seem to find any data on Fuel economy or HP...or anything for that matter so maybe I'm on stale meds & this was just a dream?? I'm going to keep looking though
I did find thid too! Variable valve timing with MD!
Displacement on Demand
In 1993 MMC developed its own variable valve timing (VVT) called Mitsubishi Innovative Valve Timing Electronic Control (MIVEC) with the MD variant. The revived MD technology was now in its second generation with improved electronic engine controls enabling the switch from 4 to 2 cylinders, which reduces the energy wasted due to pumping losses. In addition, power loss due to engine friction is also reduced. However, the final conclusions were that the major gain in fuel economy was the VVT system not from the MD feature and it was dropped in 1996.