4g18 Engines For Sale The Mitsubishi Orion or 4G1 engine is a series of inline-four internal combustion engines introduced by Mitsubishi Motors in around 1977, along with the Astron, Sirius, and Saturn. It was first introduced in the Colt and Colt-derived models in 1978. Displacement ranges from 1.2 to 1.6 L. 4g18