When the Fiero/300ZX/RX7 were out in the mid 80s, the pony cars were doing mid-6 second 0-60.....The exotic cars were in the 5 second range. So the Fiero was a good small performance car at 7.5-8.5 0-60.
Now you have great power, gazillion-speed tranys, and street tires that stick as good as mid-80s era racing tires.......I would really like to see a 1971 Mustang BOSS 351 "Super tuned" (Headers/timing/carb) and with modern shocks/tires plus a proper alignment go up against a 2020 Mustang GT....I think most people would be amazed at what that old car could do...
The first road test I read was of a Pantera in Mechanix Illustrated....It was a low 14 second quarter with a 5.1 second 0-60.....But most of the 70s 14 second quarter cars would do a 0-60 in 7 seconds...NO traction off the line at all! Modern tires would cut a second off the 0-60 and 1/2 second off the quarter with no other changes.
To be honest many of the old cars are remembered being much better than they were.
First off HP ratings were not the same. up till 1970 HP was measured as gross HP. That means on a Dino with no accessories and intake. 1971 and later it is Net HP with all stock accessories intact as well stock take.
In stock form most muscle cars even with better tires stock were 14 second cars.
I have owned these cars, driven these cars and raced these cars. I know what they could do. Yes there were the rare Hemi or BBC that did 12.9 but they were rare as they are today.
Now with some work on the engine 13’s were easy to reach with a came, intake and exhaust. Some suspension work 12’s are easy to reach.
These cars in these muscle car races are not the norm as they are blue printed and optimized in many ways the factory cars were not. I also know a few that are not legal too. A 421 looks like a 389 if it is re stamped.
The 80’s was better than the late 70’s but not much. The cars did not get faster till 1990.
The Fiero for what it was did ok with the V6. But like most sports cars it was not about over the top power but handling. Some of the best sports cars in history were not high powered but they had enough with good handling to make an interesting drive.