The Pontiac GTO had been such a success that the model became its own series in 1966 and the body was significantly revised to the familiar “coke bottle” shape, with curving lines and minimal brightwork. GM had finally dropped its corporate policy of capping engine capacity in midsized bodies and GTO sales soared to 96,946 units, which would be the highest sales year the model would enjoy.

The most popular model was the 335 bhp, 389 cid engine with four-barrel carburetor, and there were 19,045 GTOs with the 360 bhp Tri-Power setup. Later in the year the XS engine option was introduced. It was the first Ram Air engine offered, with the Air Scoop package and a hotter camshaft.

Two-thirds of all GTOs (61,279) were sold with manual gearboxes, predominantly M20 wide-ratio and M21 close-ratio 4-speeds. All had dual exhausts. This was the first year for red plastic fender liners, and prices dropped slightly from 1965.

The bubble scoop hood was carried over from 1965 and the GTO grille divided into two deep mesh recesses, with inset turn signals and GTO lettering. Quad headlights remained vertically stacked on each side. The rear panel had horizontally louvered taillights and the C-pillars swept back with a short “tunnel” back window between them. Inside, the bucket seats had more lateral support, though a Strato bench front seat was still available. The four-port dash panel remained the same, but with wood veneer. The optional console and sport steering wheel continued. Metallic brake linings and aluminum front drums were optional for $49.08, and a transistor ignition added $73.67.

A total of 15 exterior paint colors with were offered again: Starlight Black (A), Blue Charcoal (B), Cameo Ivory (C), Fontaine Blue (D), Nightwatch Blue (E), Palmetto Green (H), Reef Turquoise (K), Marina Turquoise (L), Burgundy (N), Barrier Blue (P), Montero Red (R), Martinique Bronze (T), Mission Beige (V), Platinum (W), and Candlelight Cream (Y). Two-tone paint was available in standard colors for $31.07 or in special colors for $114.27. A one-off exterior color cost $83.20.

Six interior trim colors included Black, Blue, Turquoise, Bronze, Red, and Parchment. Five convertible top colors were offered: White, Black, Blue, Turquoise and Beige. One more vinyl top color was offered this year, and the choice was Ivory, Black or Beige.

Overall, U.S. sales dipped slightly but Pontiac sold its 11 millionth car. While Pontiac’s big car sales slipped 8.8 percent, the Tempest line increased sales by 16.8 percent and the company earned more than 10 percent of the market for the first time.