The first generation Impulse was a rear-wheel drive car, and in the United Kingdom it was the first widely available Isuzu.
The second generation was available as front-wheel drive or all-wheel drive. It was the basis for the Gemini Coupe, or Geo Storm as it was known in the U.S. market.
As of 2010, the number of registered Impulses totaled only 2,300 making Impulses very rare.
In 1978, Isuzu commissioned Giorgetto Giugiaro to design a new sporty car to replace the 117 Coupe (also a Giugiaro design). They delivered several T Series Chevettes (developed in 1973 in South America) to the Italdesign studio in Italy and allowed Giugiaro free rein over the design. The result of this effort was the wedge-shaped three-door hatchback called the Asso di Fiori ("Ace of Clubs") prototype and show car, that was shown at the 1979 Tokyo Motor Show to rave reviews. Giugiaro referred to the design as his fifth "Copernican revolution", integrating the design innovations of many different previous designs into one, mass producible, vehicle. Within 48 hours of its unveiling at the Tokyo Motor Show, Isuzu fast tracked the vehicle into production with minimal changes to the design. Items that remained were the single blade front windshield wiper, and an integrated steering wheel adjustment that also moved the instrument cluster, with wiper controls and exterior lighting controls installed just behind the steering wheel on either side.
The first Piazza rolled off the production line in September 1980 in Fujisawa, Japan, available with either 120 hp (89 kW), 120 lb·ft (163 N·m) 2.0 L SOHC I4 MPFI engine, a carryover from the Isuzu 117 Coupé, or a 135 hp (101 kW), 123 lb·ft (167 N·m) 2.0 L DOHC MPFI I4 engine. Five-speed manual and 4-speed automatic transmissions were available, and all models were rear-wheel drive. For the 1985 model year, a 180 hp (134 kW), 185 lb·ft (251 N·m) turbocharged SOHC I4 engine was introduced, and the DOHC naturally aspirated engine was phased out in years that followed. Piazzas were available in a multitude of trim levels including Bella, XN, XJ, XE, XG, Nero, and others. There were three different suspension tuning levels, standard, Irmscher, and Lotus. Production continued through 1990.
For the U.S. market, this vehicle was introduced as the Impulse in 1983. For the 1983 and 1984 model years, only one engine was available, the 2.0 L SOHC I4 engine, rated at 90 hp (67 kW), 108 lb·ft (146 N·m). A MPFI turbocharged model was introduced in 1985, with a 2.0 L SOHC I4 engine rated at 140 hp (104 kW) and 166 lb·ft (225 N·m). The 1988 model year saw several changes. Mild exterior and interior changes were made to the appearance of the vehicle (including a larger rear spoiler and fixed headlights without pop up covers). The 2.0 L non-turbo engine was replaced with a 2.3 L SOHC I4 engine, rated at 110 hp (82 kW), 127 lb·ft (this engine was offered only in the U.S. market, as the larger engine would have conflicted with Japanese government regulations concerning maximum displacement for cars classified as "compact"). All Impulses received a Lotus-tuned suspension beginning in the 1988 model year, which consisted of redesigned sway bars, stiffer dampers, and a change in previous spring rates.
In the U.S. market, the Impulse was marketed as "everything standard", meaning that all Impulses came with all available equipment for the vehicle's model year, and only two trim levels offered: non-turbo and Turbo. There were, however, some special edition models, most notably the RS model of the 1987 model year, available only in white body color with pewter color trim, and featuring the stiffest suspension available on any Impulse, very close to the Irmscher suspension sold only in Japan. For the 1989 model year, a "Special Edition" non-turbo model was offered, which was equipped with the Turbo model wheels and interior trim.
The vehicle was sold as the Piazza in Europe and Australia, though introduced into these markets in 1985 or later.
In the UK the Piazza was sold in only one trim level and only Turbo form, with a 147 bhp 2.0 Turbocharged engine (4ZC1-T).
The Piazza had a shaky start in the UK with the first importer Isuzu GB, based in Maidstone, Kent going out of business in 1986, and London car dealer Alan Day ought the remaining stock of Isuzu Piazza's at a bargain price. These cars were sold by Alan Day at significantly reduced price, the main reason Isuzu GB went out of business was due to high unit price. In 1987 International Motors Group of West Bromwich (IM Group) were awarded the official Isuzu Franchise for the UK. (They also at the time represented Subaru and Hyundai in the UK). IM Group, (Isuzu (UK) Ltd) still marketed the Piazza in single trim/engine form, but they only sold the updated 'Lotus' Piazza. The earlier cars sold by Day became known as 'pre-Lotus' cars, the suspension and handling of these pre-Lotus cars was derided by UK Press as poor, especially the live axle arrangement at the rear, which by the late-80s was seen to be antiquated. The updated 'Handling by Lotus' car was available from 1987 and the handling, although keeping the live axle arrangement was transfomed by Lotus in the UK after significant development work, involving modified suspension layouts, larger brakes, specially produced dampers and Goodyear tyres. The 'Handling by Lotus' cars had updated interior and exterior equipment. The exterior having a redesigned rear, with a large 'hoop' spoiler, new rear lamps, new rear badging with 'Handling by Lotus' badges and removal of the rubber side bumper strakes for a cleaner, more modern look. The updated interior trim was mainly 'tweed' check fabric, an updated centre console, but the loss of air conditioning to keep the price down for the UK market.
Isuzu (UK) Ltd, the West Bromwich-based importer, sold the Lotus Piazza from 1987 to 1989, before concentrating on the 4WD Isuzu Trooper. They never sold the second generation Piazza in the UK.
In Australia, the Piazza was introduced very late (April 1986), and offered only in Turbo form.
Performance of the Turbo model was comparable to the Mitsubishi Starion or Dodge Conquest, as demonstrated by the fact that the acceleration and handling numbers reported by the auto enthusiast magazines were within 0.1–0.2 seconds between the vehicles.
In the U.S., the Impulse was replaced by the second generation Impulse after the end of the 1989 model year. However, in Japan, the first generation Piazza continued production and was available through the 1991 model year.