Pontiac Grand Prix Factory-Installed Highest-HP Engine Ever

The 1962 Pontiac Grand Prix was equipped with the highest factory-rated horsepower engine for the model, featuring a 421-cubic-inch V8 producing 405 gross horsepower, making it a notable early muscle car. However, due to changes in horsepower measurement standards, its net horsepower is estimated to be under 285 hp today, comparable to the 2005-2008 Pontiac GXP's performance.