| A high performance package available for Buick | | | | The engine could accelerate to 60mph in just eight |
| models including Riviera, Skylark and Wildcat was the | | | | second. Only 13,000 units were produced despite the |
| Buick Gran Sport or Buick GS. Buick was one of the | | | | improvements made to the Buick GS. |
| last manufacturers to enter the muscle cars battle. It | | | | In 1967, a new 400 cid engine was introduced, the |
| started, like other GM intermediate cars, as an option | | | | name was also changed to GS 400.The engine had a |
| on an existing model. Once the car underwent fine | | | | modern design, higher revving, an improved air |
| tuning, it would become one of the most formidable | | | | cleaner and was generally ran better than the old |
| and fearsome muscle cars of all time. | | | | engine. The major design change was the hood |
| In 1965 came the Skylark Gran Sport, an | | | | scoops were now facing forward. Along with the |
| intermediate Buick GS with the GS option added. The | | | | redesign of the engine and the exterior, the 3 speed |
| GS had the largest engine supported by GM, a 400 | | | | automatic transmission was also included. A junior |
| cid Buick V8. This was known as the "nail head" | | | | Buick GS muscle car was also formed that year, the |
| engine due to the size of its valves and was capable | | | | GS 340 but was overshadowed by its brother, the |
| of producing 32b5hp. More than 15,000 Skylarks | | | | GS 400. |
| equipped with the GS option were sold that year. | | | | In 1968, the Buick GS was now a little over 4 inches |
| The year after that, the Buick Skylark GS was | | | | shorter in length. The rear end styling was changed |
| redesigned and the performance was improved. New | | | | along with the sail creases on the sides which |
| rear sloping panels were installed that were | | | | resulted in the increase in overall weight of the Buick. |
| distinguished by blacked out grilles. Other additions | | | | A rare dealer installed option was introduced which |
| were non-functional rear-facing hood scopes and | | | | enabled 11:0:1 compression, an improved transmission |
| front fender vents. | | | | and stronger valve springs. The Buick GS production |
| The engine was now capable of producing 340bhp. | | | | ended in 1972 until it surface again in the mid 1980s. |