It was based on the third-generation Opel Kadett C on the General Motors T-car platform and came in four-door sedan and two-door coupe body styles.

[4] In November of the same year the 1600 was updated, now with square headlights and an engine with the I·CAS oxidation catalyst ("Isuzu Clean Air System") which could manage the 1978 emissions standards.

[7] The ignition system was now of a transistor less type, and the trunk lid was now opened remotely (not added to the Gemini 1600 until the end of December).

These models also came with a shortened remote throw manual shift lever and optional factory LSD differential.

After the front-wheel-drive second generation Gemini appeared in early 1985, the old rear-wheel drive version nonetheless continued to be built.

It first appeared in late 1975, for the 1976 model year, and replaced the German-built Kadett which had become too expensive as a result of the weakening dollar and rising costs in Germany.

[11] Road & Track decried the switch, stating that the Isuzu felt "built to a price" and that unlike the real Opel, it was "one of our least favorite cars.

"[12] In 1978 a "Sports Coupé" was added to the lineup, its changes being limited to the paint, different steel wheels, sporty mirrors, and a spoiler.

For 1979 the car received a light cosmetic update with ribbed velour trim, a few new paint options, and rectangular headlights.

The I-Mark was offered with four-door sedan or two-door coupé bodywork with either engine, in Deluxe or fully equipped LS (added for the 1982 model year) trim.

In addition to sedan and coupé models, Holden in Australia produced the Gemini as a three-door station wagon and three-door panel van, which were derived from the Opel Kadett C Caravan and Vauxhall Chevette wagon, with Isuzu Gemini front panels.

The car received Isuzu badging for the first few years in this market, as the brand had already been established by the earlier Bellett, which had also been assembled locally.

In Europe, the Gemini was equipped with the 1.6-liter engine which produced 68 PS (50 kW) DIN there; the discrepancy in stated power (down 32 percent) may have been entirely due to the differences to the SAE (gross) measuring system used on Japanese market cars.

The FF Gemini underwent a facelift in February 1987, receiving a more aggressive front styling with wraparound headlight as well as other minor changes.

The position of the rear license plate garnish for the sedan model has been moved from the trunk lid to the center part of the bumper.

Other differences include the amber turn indicators lens now having been dropped, and an addition of side marker lights.

Sales were limited to coastal markets initially, as import quotas restricted the number of cars General Motors could sell in the United States.

With a delayed introduction of the upcoming Stylus (third generation Gemini), Isuzu largely abandoned the passenger car segment for nearly a year, selling mostly leftover stock of the old Impulse.

For GM, this was an entry-level vehicle to attract young buyers and to compete with Japanese midsize cars in the US market.

There was also a Spectrum Sport Coupe package (hatchback only) on offer, using the standard engine combined with some of the Turbo's equipment, such as a sporty steering wheel, different rear view mirrors, a rear spoiler, fully body colored exterior (grille, bumpers, door handles, etcetera), and the uprated F41 suspension.

[26] The 1989 Geo Spectrum (introduced in June 1988 as an early 1989 model year) was only available with the naturally aspirated 1.5-liter engine in a single equipment level, with either the three-door hatchback or four-door sedan bodywork.

In North America, the base Stylus "S" model received a 95 hp (71 kW) 1.6 L SOHC version of the 4XE1, available in 5-speed manual or 3-speed automatic transmissions.

The 1990 and 1991 top-line Stylus "XS" models had a 125 hp (93 kW) 4XE1-UW 1.6 L naturally aspirated DOHC engine only available with a 5-speed manual transmission when introduced, and received the 4XF1 140 hp (104 kW) 1.8 L naturally aspirated DOHC engine with the 5-speed manual in its final 1992 model year.

The DOHC Stylus (both "XS" and "RS") would be dropped after 1992, leaving the lone SOHC "S" trim for the final 1993 model year to stand alongside the Geo Storm platform triplet.

The third platform triplet, the Impulse, would also be withdrawn after 1992 and was sold in Canada for 1993 only as the Asüna Sunfire, as Isuzu was preparing its passenger car exit from the US market in July 1993.

The higher trim level packages offered "ZZ handling by Lotus" and "specification Irmscher" as the performance models in the lineup, but was carryovered from previous generations.

The suspension packages that were installed on the second generation Isuzu Piazza were also shared on the Gemini sold in Japan, including the four-wheel steering setup.

After a corporate restructuring, Isuzu decided to abandon passenger car production and focus on commercial truck and SUV production, as the Trooper and the Rodeo found many buyers internationally, with badge engineered versions sold under a variety of brands and names across different markets.

As usual, the Gemini was available in a much more limited lineup than that of the related Honda version, with only one bodystyle (four-door sedan) and either a 1.5- or a 1.6-litre engine.

In Australia, the 1982–1984 Holden Gemini was assessed in the Used Car Safety Ratings 2006 as providing "significantly worse than average" protection for its occupants in the event of a crash.