What American muscle car had highest horsepower all time?

The title of "highest horsepower American muscle car of all time" is a bit tricky because it depends on how you define "muscle car" and whether you're talking about factory output or aftermarket modifications. There's no single definitive answer.

However, strong contenders for the highest *factory* horsepower include versions of the:

* Dodge Challenger SRT Hellcat Redeye: This model boasted over 797 horsepower. While some later models might have topped it slightly through special editions or limited runs, it held a leading position for a significant period.

It's important to note that numerous aftermarket modifications can push horsepower far beyond factory numbers in many muscle cars. Therefore, any claim of the "highest horsepower" needs to specify whether it's factory or modified.