In early 1962 Corvette chief Zora Arkus-Duntov began in the development of a car known inside the division simply as the “Lightweight.” The objective was overall victory at FIA endurance races, including the 24 Hours of Le Mans. The project had the approval of Chevrolet head Bunkie Knudson, but due to the ban on all racing activities by the corporate leaders at GM, the plan was a tightly-held secret.

Five Grand Sports were built. The cars were designed to be as light and as powerful as possible. The chassis, bodies, and virtually all other components were specially designed and handmade by the team of engineers – even small items like hood and door hinges were hand-fabricated out of aluminum. With this extensive use of aluminum, combined with a lightweight tube frames, fabricated suspension, and special ultra-thin fiberglass bodies, the Grand Sports weighed under 2000 pounds – 1100 pounds less than production Corvettes.

In 1963, Grand Sports 003 and 004 were extensively raced, undergoing continuous development over the season. At the end of the year, all five cars underwent engine, drive-train, and body upgrades. Most significantly, the almost stock engines were replaced with full-race aluminum 377 cubic inch engines that produced over 550 horsepower. The upgrades proved themselves at Nassau in December, with Grand Sports 003, 004 and 005 overwhelming the Cobras and Ferraris. Then, as a final step in the Grand Sport’s evolution, the engineers converted 001 and 002 to roadsters for the upcoming 1964 Daytona endurance race. These two roadsters became the lightest-weight and fastest Grand Sports of all.

But in early 1964, higher-ups at General Motors ordered the project canceled, and the cars destroyed. Instead, the engineers quickly transferred 003, 004 and 005 to private racers, and somehow managed to keep the two roadsters hidden at Chevrolet for two more years.

Finally in 1966, the roadsters were sold to Roger Penske. They were repainted (one blue, one white), and converted to 427 power.