A fastback is an automotive styling feature, defined by the rear of the car having a single slope from the roof to the tail. The kammback is a type of fastback style. Some models, such as the Ford Mustang, have been specifically marketed as fastbacks, often to differentiate them from other body styles (e.g. coupe models) in the same model range. The 4-door coupe is a common branding term used today to describe fastback sedans. Definition A fastback is often defined as having a single slope from the roof to the rear of the vehicle. The term "fastback" is not interchangeable with "liftback"; the former describes the shape of the car, and the latter refers to a roof-hinged tailgate that lifts more upwards than rearwards. More specifically, Road & Track have defined the fastback as A closed body style, usually a coupe but sometimes a sedan, with a roof sloped gradually in an unbroken line from the windshield to the rear edge of the car. A fastback naturally lends itself to a hatchback configuration and many have it, but not all hatchbacks are fastbacks and vice versa. In the case of the Ford Mustang, the term "fastback" is used to differentiate against the coupé notchback body style, which has a steeper rear window followed by a horizontal trunk lid. History Automobile designers in the 1930s began using elements of aircraft aerodynamics to streamline the boxy-looking vehicles of their day. Such designs, that were ahead of their time when exhibited during the early 1930s, included a droplet-like streamlining of the car's rear; a configuration similar to what would become known as the "fastback" 25 years later. Merriam-Webster first recognized the term "fastback" in 1954, many years before the popularization of the term "hatchback", which entered the dictionary in 1970. Opinions vary as to whether the terms are mutually exclusive. Early examples of fastback cars include the 1929 Auburn Cabin Speedster, 1933 Cadillac V-16 Aerodynamic Coupe, 1935 Stout Scarab, 1933 Packard 1106 Twelve Aero Sport Coupe, Bugatti Type 57 Atlantic, Tatra 87, Porsche 356, Saab 92/96, Standard Vanguard, GAZ-M20 Pobeda, and Bentley Continental R-Type. North America and Europe In North America, the numerous marketing terms for the fastback body-style included "aerosedan", "club coupe", "sedanette" and "torpedo back". Cars included Cadillac's Series 61 and 62 Club Coupes, as well as various other models from General Motors, Ford, and Chrysler. By the early 1940s