This was CSP. Street Prepaired opens up a lot of possibilities so things that seemed level at the dealership get out of balance on the track. In SP the intake and exhaust are more or less free, meaning full race header, aftermarket fuel injection, shocks and springs are free, you can do what you need to get camber adjustment, so is tire and wheel size, cams. Power gains would be extremely easy. Having seen many cars Prepaired to this level it isn't hard to imagine making a pretty wicked Fiero.
The real question is, and I'm not talking about racing here: are the big engine and 400lbs of useless dead weight the result of the car being aimed at a different segment or of it just being...bad?
In the end, the Fiero was more powerful than most Miatas sold. They only have 165 HP or something like that now with the new car. I don't think most people in the market for a throwaway priced retirement car give a shit about power.
Btw, I just did some more reading and I was wrong. The Fiero sold 370,000! So that means it outsold the Mk1 Miata! But still got canned because...I don't know. Maybe they just wanted to shut the plant, that does happen sometimes.
As for autocross, I don't do it anymore. I got tired of waking up at 5:30 am on a Saturday to spend three minutes on the track and 9 hours baking in the sun. I'm not very competitive by nature so track days are fine with me. That way you get two hours on the track and you don't have to do jack. I also really suck at autocross and I think I always will. It's not that I can't drive, I do fine on a road course, is that autocross really is its own animal. I went into it thinking that it's simply low level motorsport, and it is, just above drag racing in its accessibility, but it has its own weird technical side due to the hyper tight courses and intense competition. You have to simply manhandle the shit out of your steering wheel for one thing, which is the opposite what you do in most kinds of automobile racing. You'll walk the course and then do your timed laps without every having driven it. You need to memorize that shit instantly. It sucks! I suck at it anyway.
I must say I've had some good times in Solo and ridden in some wild fast cars. For people who need to know who's fastest it's one of the most competitive sports in the world. People who haven't seen high level Solo wouldn't believe how refined these cars and drivers are. They drive 10/10 ALL THE TIME because he run is only 58 seconds or whatever. To see a top level Cobra Mustang and a Rabbit both hit he same time on the index to .001" is something else.
Btw, the Chevette actually had a semi-decent career as a rally car in the early 80s, look it up. It being RWD and simple apparently gave it an advantage on paved courses.