In 1962, LeMans continued on this path, adding a convertible to the offerings. Though all four body styles -- coupe, sedan, convertible and station wagon -- were available as Tempests, there was no four-sedan or station wagon LeMans. There was also no pillarless hardtop version of either Pontiac.
The next year, in 1963, the LeMans name was still only used on coupes and convertibles, but the name was officially made its own model. This would last for just one year. It's these 1963 cars of both nameplates that had the high-performance 326 in³ V8 option (actually 336 ci for that one year only) and specially modified versions of them became the Super Duty cars of racing lore. The Tempest line was upsized to an intermediate sized car on the new GM A platform in 1964, and the LeMans returned to its role of Tempest trim upgrade with a new 215 in³ six-cylinder and a redesigned 326 in³ V8.
Shortly after the start of the 1964 model year, the LeMans became available with a new performance package designated as the GTO, or Gran Turismo Omologato. The GTO option was priced at just under US$300 and included a larger 389 in³ V8 from the full-sized Pontiac line that put out 325 or 348 hp, a three-speed floor shift manual transmission with Hurst shifter, heavy-duty suspension, red-line Tiger Paw tires, and GTO nameplates. GTO sales ended up at 32,000 for the first year, well beyond initial estimates of 5,000 units and accounted for a large share of Tempest/LeMans sales. The success and the image of the GTO helped increase sales of lesser Tempest and LeMans models in the coming years, placing the Pontiac brand into third place in total industry sales after Chevrolet and Ford.Source: Wikipedia.