When the first set of Mustangs were sent to Germany they couldn't release from the ports using that name (there was a patent on it there) so they had to wait for new registration papers to come worth the "pony" name on them, and then we're let into the county for the dealers to sell them.
I read that in fact not too long ago I will try to find that article to place here for others to read as well.
Like every one else, we had the same story like you said but it seems there was this story too lol
They say the Mustang was the first "pony car" engines in small cars etc but the Barracuda was actually out before the Mustang so that is wrong also..
Barracuda, first pony car by 6 months ...
