Hot rod is usually an older automobile with an improved engine or body design. Hot-rodders build their cars for either racing or normal driving. Hot rods built for driving often are referred to as street rods. Popular hot-rod models include Ford Model T's and Model A's and Chevrolets of the 1930's and 1940's. Hot-rodders seek to achieve the latest technology in brakes, steering, engines, and other parts to make the car run perfectly.