The Fiero was a great concept. But it faltered a bit in practice.
By the time GM started putting the V-6 in the thing the die was cast and no one was buying the things.
Also, the car could not be towed under any circumstances. If it broke bad enough to need to be ferried to a garage it had to be loaded onto a flat-bed. Towing put too much stress on the spaceframe and ruined the car.
As duke said, the Fiero was not your typical sporty car of the '80s from an American manufacturer.
But, like the MR2, Pontiac took an established passenger car motor, and shoe-horned it into a modern sporty package.
It was originally concieved as a runabout or a commuter car. The base version with the 98HP 2.5 liter I-4 turned about 35 mpg on the highway. (Also unheard of in an American car of that era). The car only lasted 4 model years 1985-1988.
Its most auspicious showing, was the role several modified versions played in a very bad action movie, "Action Jackson" starring Carl Weathers.