The 1964 GTO is the one that started the whole Detroit Musclecar craze--but it almost never happened. GM's corporate policy wouln't allow such a lightweight car with such a huge engine, but Pontiac "finessed" the rules by making the GTO an option to the Tempest Le Mans. The cost of this option? Oh, about two hundred bucks.
With power-to-weight ratios like rocket sleds, Novas became immediate favorites of the muscle car crowd. If a 327 or a 350 wasn't enough, how about a 375-horsepower 396 in a Chevy II Nova? If you had about three grand and nerves of steel, you could have owned one.
By 1967, the next generation was ready for a Mustang and Thunderbird fusion - the car they all wanted was the Mercury Cougar.