The 1966 Mustang debuted with moderate trim changes including a new grille, side ornamentation, wheel covers and gas cap. An automatic transmission for the "Hi-Po," a large number of new paint and interior color options, an AM/eight-track sound system, and one of the first AM/FM monaural automobile radios were also offered.
The 1966 Mustang removed the Falcon instrument cluster; the previously optional features, including the round gauges and padded sun visors, became standard equipment.
The 1966 Mustang is differentiated by variations in the exterior, despite similar design. These variations include the emblem on the quarter-panels behind the doors. In 1966 the emblem was smaller in height and had three horizontal bars extending from the design, resembling an "E". The front intake grilles and ornaments were also different.
The 1966 version was a "slotted" style.