Since the mass production of Henry Ford's Model T, car enthusiasts have been redesigning, rebuilding, and reengineering their vehicles for increased speed and technical efficiency. They purchase aftermarket parts, reconstruct engines, and enhance body designs, all in an effort to personalize and improve their vehicles. Why do these car enthusiasts modify their cars and where do they get their aftermarket parts? Here, David N. Lucsko provides the first scholarly history of America's hot rod business. Lucsko examines the evolution of performance tuning through the lens of the 34-billion speed equipment industry that supports it. As early as 1910, dozens of small shops across the United States designed, manufactured, and sold add-on parts to consumers eager to employ new technologies as they tinkered with their cars. Operating for much of the twentieth century in the shadow of the Big Three automobile manufacturers-General Motors, Ford, and Chrysler-these businesses grew at an impressive rate, supplying young and old hot rodders with thousands of performance-boosting gadgets. Lucsko offers a rich and heretofore untold account of the culture and technology of the high-performance automotive aftermarket in the United States, offering a fresh perspective on the history of the automobile in America.