[1] Two sedan versions were offered: the SEAT 131 L, featuring rectangular front lamps, 1438 cc OHC engine and four-speed gearbox, and the SEAT 131 E which featured four round headlamps, a 1592 cc DOHC engine, and a five-speed gearbox.

In 1977 the 131 Automatico (Automatic gearbox) was released and the following year a very short production of the SEAT 131 CLX 1800 was offered.

The implementation of the diesel engines in the SEAT 131 range took place almost four years after its launch.

This would practically exclude the use of the SEAT 131 in the taxi fleet,[citation needed] in spite of its significant performance in both comfort and roominess.

In the meantime however, for a great number of Spanish taxi owners and other professionals who were opting for the SEAT 131 as their taxicab of choice, a very common practice was the after-market replacement with a diesel engine of a newly purchased gasoline-powered SEAT 131.