The Tempest was introduced as an entry-level compact in September 1960 for the 1961 model year. Sharing the new monocoque (unibody) Y platform with the Buick Special and Skylark, and Oldsmobile F-85 and Cutlass, the model also appeared under the LeMans nameplate (largely beginning with the 1962 model year, though Pontiac also manufactured a few 1961 Le Mans coupes).
For 1964, the platform was redesigned with a full-size frame, and renamed A-body. The Tempest name was discontinued after the 1970 model year in favor of Le Mans, a nameplate previously used for upmarket versions of that series.
Engine offerings for the 1965 Tempest were the same as 1964, except the 326 HO was uprated to 285 hp (213 kW; 289 PS) and GTO 389's uprated to 335HP and 360HP via higher rise intake manifolds. Styling changes included a new split grille with vertical headlights similar to the larger Pontiacs, revised taillights and a more slanted rear deck. A two-door hardtop coupe was added to the Tempest Custom line, while the Le Mans got a four-door sedan with a plush interior done in Preston Cloth trim similar to the full-sized Bonneville Brougham.
Source: Wikipedia (original)