20: Pontiac GTO
If the Mustang pioneered the pony car segment, then the GTO pioneered the muscle car world. When John DeLorean set out his plans to create the Pontiac GTO, he had to cut through a lot of red tape. The top brass at GM didn’t see the logic in creating a car that was like the GTO. So DeLorean made the GTO a trim package on an existing car and the rest is history (via Hagerty).
The GTO redefined what a muscle car should look and drive like and buyers clamored for these vehicles. The styling of the GTO completely changed what car fans expected in a muscle car and that was a great revolution. With the GTO came a plethora of other muscle cars including the Chevelle and the Cutlass. The muscle car era is widely considered one of the best times for domestic carmakers and the GTO was responsible for that.