A fastback is an automobile with a roof that has a consistent slant from the front of the cabin to the rear of the car. As the roof proceeds to the rear, it gets closer to the base of the car. At the tail of the automobile the fastback will either curve directly toward the ground or end abruptly. The design is frequently used due to its ideal aerodynamic properties. The term can be used to describe either the design or the car that is designed in such way.
The slope of the fastback can either be curved or more straight, whichever the manufacturer preferred. The angle of the slant, however, varies from vehicle to vehicle. While some have a very slight angle of descent, other cars have an extremely pronounced decline. The angle of the fastback is constant, never breaking, until the card ends.
Though a consensus has not been reached on which car was the first to employ a fastback design, some have speculated that the Stout Scarab, produced in the 1930s, may have been one of the first automobiles to use such a design. Also considered to be the world's first minivan, the Scarab featured a roof that gently and then sharply sloped at the rear, resembling a tear drop shape. Other auto manufacturers eventually took notice and began using similar designs before they found the ideal slope for aerodynamic purposes.
One advantage of the fastback design is its superior aerodynamic properties when compared to many other automotive forms. As any vehicle travels through a fluid, such as air or water, an opposing force called drag will develop as the velocity of the vehicle increases. In other words, a car traveling through the air encounters drag, which slows the car down and adds pressure, due to how the air curls around the car as the air passes over it.
Fastback automobiles have a very low drag coefficient, which allows them to achieve greater speeds and fuel efficiency with the same amount of power and fuel as most other types of cars. The low drag coefficient makes this design ideal for sports and racing cars.
Hatchbacks and fastbacks are often confused. A hatchback is any automobile with a rear windshield and trunk door, or hatch, that are affixed to one another and operate as a single unit. There are often hinges at the top of the rear windshield that raise the hatch and window upward. Many, though not all, fastbacks do utilize a hatchback design. A fastback can be a hatchback and vice versa.