OK I’m going to throw one into the discussion here and I have copied and pasted the information on it as listed in Wikipedia. It is a car most people are not familiar with much less ever heard of. So my nominee is the 1957 Rambler Rebel.
" The Rambler Rebel is an automobile that was produced by the American Motors Corporation (AMC) of Kenosha, Wisconsin for the 1957–1960 model years, as well as again for 1966 and 1967.
Introduced as a stand-alone model in one body style, the 1957 Rambler Rebel is credited for being the first factory-produced intermediate-sized high-performance car. This later became known as the muscle car market segment. It was also to be among the earliest production cars equipped with electronic fuel injection. American Motors surprised most observers with the December 1956 introduction of the Rambler Rebel – “a veritable supercar”. The new 1957 model debuted as a high-performance vehicle that combined AMC’s lightweight 108-inch (2,743 mm) wheelbase Rambler four-door hardtop body with AMC’s newly introduced 327 cu in (5.4 L) V8 engine. This made it the first-time that a large block V8 was installed in a mid-size car in the post-World War II marketplace. General Motors, Ford, and Chrysler offered no intermediate-sized cars whatsoever."
Below is a link from youtube.com regarding this car. Watch this youtube clip and listen to the owner explaining how this 1957 Rambler Rebel is the first muscle car and how he further explains, as I said, that nobody has ever heard of it. Also, notice he says the ONLY car produced in 1957 that was faster was the Fuel Injected Corvette. And yes, that would mean it was faster than the Chrysler 300 C.
PHOTO BELOW OF A 1957 RAMBLER REBEL