The Lotus Seven was introduced in 1957 and was the company’s first serious production car. The 7 would become an unqualified commercial success for Lotus, one which exemplified company founder Colin Chapman’s ‘added lightness’ performance maxim. The name ‘Seven’ was left over from a model that was abandoned by Lotus, which would have been a Riley-engined single-seater that Lotus intended to enter into Formula Two competition in 1952 or 1953. Instead, the car was built around Chapman’s chassis as a sports car by its backers and called the Clairmonte Special.
During its production lifespan a great deal of development work was applied to the 7 along four distinct series. The original S1 had a tubular spaceframe chassis, wishbone and coil spring independent front suspension, a live rear axle, and simple open bodywork. The S1 would establish the basic formula and components of the 7, all of which would continue through all four iterations of the car. It was designed to accommodate a variety of engines, with the basic powerplant being the 40 horsepower, 1172cc side-valve four-cylinder Ford engine, with BMC A-Series and Ford 105E overhead valve units available later. When the 7 received the 1,098cc Coventry Climax engine, the cars were known as the ‘Super 7.’
In 1960, Lotus introduced the S2 which brought with it a simplified and revised spaceframe. The Super Seven was now available with a Cosworth-tuned Ford 1,340cc engine intended for SCCA racing in the United States, later in 1.5- or 1.6-liter displacements. The main update of the following S3 version, introduced in 1968, was a strengthen chassis with stressed front bulkhead. Caterham production would take over during the S3 run. In 1970, Lotus radically changed the shape of the car to create the slightly more conventional sized Series 4, with a squarer fiberglass shell replacing most of the aluminum bodywork. It also came with some ‘luxuries’ as standard, such as an internal heater matrix.