1. 1969/1970 Ford Mustang Boss 429
Ford built the Mustang Boss 429 to homologate its most potent V8 for its NASCAR-competing Torino. According to Hemmings, the Boss 429 package cost $1200 and provided you with 375 hp. Well, 375 advertised horsepower. In its day, the Boss 429 was probably making around 475 hp, but Ford wanted to keep insurance companies in the dark.
2. Studebaker Super Lark
In its final days as an automaker, Studebaker offered a proto-muscle car in the form of the Super Lark (pictured right). Equipped with the 289-ci “R2” engine, the Super Lark was good for 0-60 mph in around seven seconds and a top speed of over 130 mph. Studebaker even offered a supercharged Super Lark that made around 335 horsepower, but no one knows how many were actually built. Just one example is a known quantity.