So what IS a muscle car?

Dfr360cuda said

I'm sure I forgot more too.
But GTO was not the first muscle car like they always say.
And Mustang was not the first pony car.

Click to expand...

I was told once, the GTO is called the first muscle car because there was a company wide edict which said "no engines over 400 CUI in midsized cars
So the good people at pontiac grabbed a 403 CUI, labeled it a 399 and dropped her in a midsized car

(Gimme a minute to see if I can back that memory up)

Edit:
Found the book I had in mind...turns out I was mixing two brand X models, the 64 GTO and the 65 buick skylark grand sport