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. It 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 PS (88 kW), 120 lb·ft (163 N·m) 2.0 L SOHC inline-four MPFI engine, a carryover from the Isuzu 117 Coupé, or a 135 PS (99 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. In April 1984, a 180 PS (132 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 US 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 1987 model year had the RS model which came with a 4ZC1 turbo engine.