I first got fiero fever when I saw my uncle's new blue coupe. I only got to see my uncle once a year, and I always told him every year to let me now when he was tired of it, and I would buy it. He called in 1999, and I drove a 16 hour round trip to pick it up. It was my first fiero. Fiero fever is chronic; I am sure your nephew will get 'his' fiero eventually.
I always liked notchback coupes and didn't really consider fastbacks as fieros, so I never confused other cars for fieros. However, my brother liked fastbacks and would confuse a dodge daytona with a fastback. BTW, I now like fastbacks too!