"The Mustang was originally available as either a hardtop or convertible, but during the car's early design phases a fastback model was strongly considered. In 1965, the Shelby Mustang was born, it was available only in newly introduced fastback body version with its swept-back rear glass and distinctive ventilation louvers. The standard interior features of the 1965 Mustang included adjustable driver and passenger bucket seats, an AM radio, and a floor mounted shifter in a variety of color options. Ford added additional interior options during the 1965 model year. The Interior Decor Group was popularly known as "Pony Interior" due to the addition of embossed running ponies on the seat fronts, and also included integral armrests, woodgrain appliqué accents, and a round gauge cluster that would replace the standard Falcon instrumentation. Ford later offered an under-dash air-conditioning unit, and discontinued the vinyl with cloth insert seat option, offered only in early 1965 models. "