Regarding this recent thing about the Impulse/Piazza:
One other thing that is worth mentioning as to why these are relatively rare... the MSRP.
Using 1987 as an example and using NADAguides.com for data:
Isuzu Impulse RS turbo: $14,639
Ford Mustang GT: $11,835
Chevy Chevette CS 2 door Hatchback: $4995
Factoring in the MSRP, which would you pick? The tarted up Fairmont, the tarted up Chevette, or the actual Chevette?