The Sigma nameplate first appeared in 1976 on the Galant Σ, a mid-size Mitsubishi sedan that marked the third generation of the Galant line. Mitsubishi chose the Greek letter sigma to suggest a “summation” or culmination, reflecting the car’s role as a showcase for the company’s engineering at the time. In the early and mid-1980s, the Sigma badge continued to be used on Galant-based sedan and hardtop variants in Japan, and the name also carried over into several export markets.
After that earlier run, Mitsubishi revived Sigma in 1990 for a very different car: a comfort-focused four-door sedan derived from the Diamante. This later Sigma sat near the top of Mitsubishi’s passenger-car range and was positioned as a more relaxed, upscale alternative to the sportier Diamante. It was sold in Japan and in some overseas markets, including Europe and North America in various forms, before the nameplate faded away in the mid-1990s.
Because the Sigma badge was used in more than one distinct production period, its history should be treated as a discontinued-and-revived nameplate rather than a single continuous run.