The Lotus 30 used a curvilinear fibreglass body mounted over a backbone chassis — a layout first seen in the front-engined Lotus Elan. In the 30, the configuration was reversed to place the engine behind the driver in a mid-engined arrangement. The backbone chassis carried the same "pickle fork" structure as the Elan, though on a much larger scale to accommodate the American V8.
The powerplant was the 4.7-litre (289 cubic inch) Ford V8, the same unit used in the Ford GT40. Drive was transmitted through a five-speed ZF synchromesh 5DS20 transaxle, chosen for its greater torque tolerance compared to the Colotti unit that had proved fragile in the earlier Lotus 19B. The car ran on 13-inch wheels and used solid disc brakes at all four corners. Headlights, taillights, and a windscreen wiper were fitted, reflecting the FIA Group 4 Sports Car regulations of the period, before Group 5, 6, and 7 categories were formally created by the FIA in 1966.
Lotus engineer Len Terry, asked by Chapman to review the draft concept, considered the design so fundamentally flawed that he declined any involvement with the project.
The Lotus 30's core problem lay in the torsional rigidity of the backbone chassis. Scaled up from a design suited to the lighter, lower-powered Elan, the chassis flexed under the torque demands of the V8 and the progressively faster tyres of the mid-1960s. This flex fed directly into chassis and suspension failures during competition. As horsepower requirements and tyre technology evolved, the original design was pushed well beyond its intended limits.
Jim Clark, then at the height of his Formula One powers with Lotus, drove the 30 in several events and extracted some promising results before the car was withdrawn from development. Clark's commitment to a car widely regarded as dangerous underlined the respect drivers of the era were expected to show toward their constructor's projects.
The bluntest verdict came from American driver Richie Ginther. When asked what he thought of the Lotus 40, the 30's successor, Ginther replied: "Same as the 30 but with ten more mistakes." The Lotus 40 was introduced in 1965 with 15-inch wheels, vented disc brakes, and a larger engine, but remained as troublesome as its predecessor.
Despite its competition failures, the backbone chassis concept itself was not without merit. At lower power outputs, the layout proved entirely adequate, and it formed the structural basis for the Lotus Europa — a road car that became one of the most analytically satisfying sports cars of the 1960s and 1970s. With further development, the same chassis architecture underpinned the Lotus Esprit series through into the 1990s.
The Lotus 30 stands as a cautionary example in motorsport engineering: a chassis concept transplanted from one power class to another without sufficient structural reinforcement. Chapman's willingness to pursue bold ideas regardless of conventional wisdom produced both his greatest triumphs and, in the case of the 30, some of his most instructive failures.