What is the rarest existing muscle car?
The rarest existing muscle car is the 1970 Plymouth Superbird. Only 1,920 Superbirds were built, and of those, only 135 were equipped with the 440 Six Pack engine. The Superbird was designed to compete in NASCAR, and it featured a distinctive aerodynamic nose cone and rear wing. It was also one of the most powerful muscle cars of its era, with a top speed of over 170 mph.