Most powerful muscle car of the 60s and 70s?

Defining the "most powerful" muscle car of the 60s and 70s is tricky because power ratings varied depending on the year and how they were measured, and different manufacturers had different approaches to horsepower claims. However, strong contenders for the title consistently include:

* 1969 Plymouth Road Runner Superbird: This car, specifically with the 426 Hemi engine, is frequently cited as one of the most powerful. The aerodynamic design complemented the immense power, resulting in a car capable of high speeds.

* 1970 Plymouth Superbird and Dodge Daytona: Similar to the Road Runner Superbird, these cars utilized the aerodynamic body to maximize the output of their powerful engines, most notably the 426 Hemi.

* 1969 Dodge Charger Daytona: Again, the aerodynamic design of the Daytona coupled with the 426 Hemi engine placed it in contention for the most powerful.

* Various Chevrolet models with the LS6 454ci engine: Chevrolet offered several models (Chevelle, Camaro, etc.) with this powerful big-block V8, making strong claims to the title. However, these cars didn't benefit from the same aerodynamic advantages as the Mopar (Dodge/Plymouth) offerings.

Ultimately, there's no single definitive answer. The "most powerful" depends heavily on how you define power (net horsepower, gross horsepower, track performance, etc.). All of the models listed above consistently rank near the top of lists compiling the most powerful muscle cars of that era.