Wikipedia defines a muscle car as:
The term
muscle car generally describes a
mid-size car with a large, powerful engine (typically, although not universally, a
V8 engine) and special trim, intended for maximum acceleration on the street or in
drag racing competition. It is distinguished from
sports cars, which were customarily considered smaller, two-seat cars, or GTs, two-seat or
2+2 cars intended for high-speed touring and possibly
road racing. High-performance
full-size or
compact cars are arguably excluded from this category, as are the breed of compact sports coupes inspired by the
Ford Mustang and typically known as
pony cars, although few would dispute a
big-block pony car's credentials as a muscle car.
An alternate definition is based on power-to-weight ratio, defining a muscle car as an automobile with (for example) fewer than 12 pounds per rated horsepower. Such definitions are inexact, thanks to a wide variation in curb weight depending on options and to the questionable nature of the SAE gross horsepower ratings in use before
1972, which were often deliberately overstated or underrated for various reasons.
