How are today’s as/ah cars different

MAPS said
LO23M8B
Thanks for the history class of yesteryear cars from motorcity herself...
I have a question, does anyone know why/how, the Mustang got the "Pony" handle ?
Has nothing to do with Mustang, horses = ponies... etc.
Thanks.
MAPS

Because back in the day they were considered pony cars not muscle cars. They were smaller and had smaller engines (at least when they started out).