Every horsepower figure printed on a 1960s muscle car brochure was a negotiation between engineering and marketing, and both sides cheated. Some engines were inflated on paper to win showroom arguments. Others were deliberately understated to slip past insurance underwriters and racing sanctioning bodies. Sorting out which classic muscle cars actually made the most power means throwing out the window sticker entirely and looking at what these engines really did. Read on to find out which numbers hold up.