Forced to adapt to the robotic paradigm of efficiency introduced by Japanese motorcyclemakers, Harley-Davidson answered in 1984 with the Evolution engine. The Evo was the product of 15 years of development, but the result was well worth the wait: a lighter, longer lasting, more fuel-efficient alloy engine that retained the look, sound, and feel of the manufacturer's classic iron powerplants, while laying the foundation for phenomenal future successes. This all-color history is a tribute to the design and development of the Evo engine and the motorcycles it powers. From the Milwaukee drawing board to the brutal testing at Talladega Speedway and the wildly popular motorcycles that resulted, the Evo story is retold in the context of marketing considerations that helped Harley-Davidson transform its product from the transportation of choice among society's outcasts to an exciting new medium of expression for America's affluent.