In the early days, they called them by the descriptive terms Soup-Ups, Go Jobs, or Cut-Downs. The name Hot Rod came later, but it's the name that stuck - two words that police officers and parents said as a curse and that kids whispered with awe.  And then came Customs, Rat Rods, Street Rods and more. It was an all All-American fad, this need for wheels and speed with an individual touch. And through the years, hot rodding became an Art -- with a capital "A".
Source: "The All-American Hot Rod"