The GTO is a classic muscle car and the 1966 has curvaceous styling with kicked-up rear fender lines for a "Coke-bottle" look, and a slightly "tunneled" backlight. The tail light featured a rare louvered cover, only seen on the GTO.
The GTO became a separate model series, rather than an optional performance package, with unique grille and tail lights, available as a pillared sports coupe, a hardtop sans pillars, or a convertible. Also an automotive industry first, plastic front grilles replaced the pot metal and aluminum versions seen on earlier years. New Strato bucket seats were introduced with higher and thinner seat backs and contoured cushions for added comfort and adjustable headrests were introduced as a new option. The instrument panel was redesigned and more integrated than in previous years with the ignition switch moved from the far left of the dash to the right of the steering wheel. Four pod instruments continued, and the GTO's dash was highlighted by walnut veneer trim.