A hot rod is a fast car used for racing, especially an old car fitted with a new engine. an old car that has been fitted with a powerful engine to make it go faster. Automobile rebuilt or modified for high speed, fast acceleration, or sporty appearance. A wide range of automobiles may be called hot rods, including some of those used in drag racing as well as those used in recreational cruising. They may be composed of used or new parts. Some are intended primarily for exhibition