What could have been: 1964 Ford Mustang

Most of us have seen these already. Many times.

I just never get tired of them. A four door version of the original Mustang.
I just wonder why this was never made. Since the Mustang turned out to be so popular, why not have different versions?

Funny that Chevy and Pontiac never jumped on the idea either for the Camaro and Firebird…