The car that is respected among car historians that arguably is known as the first American muscle car, the Pontiac GTO broke a few rules when it was in the testing phase of its design. Pontiac, a General Motors company, had the GTO model with a 389 Cubic inch V8 engine... General Motors, at the time, did not allow for more than 330 cubic inches in their engines.
The first year of the GTO was 1964 and this model was a mean looking car that also had a convertible option.
In 1967, the GTO got an upgrade from the previously mentioned 389 cubic inch engine to a full 400 cubic inch engine which could produce up to 360 horsepower. The 1967 was also the model year after the 1966 version of the GTO which had some major body changes (Few changes from '66-'67).
The Pontiac GTO remained a powerhouse through the mid 70's as the 1970 model upgraded to 455 cubic inches with 500 foot-pounds of torque. In the exterior, the GTO looked even more mean and stylish with body changes to the headlights, grill, and body-lines on the car.
