Colin Chapman's first foray into single-seater racing, the 12 appeared in 1957. It featured a number of important innovations Chapman would use on later models. To better use the power of the Coventry Climax engine, it was designed, as usual, for low weight and low drag, relying on a space frame. It placed the driver as low as possible, eliminating the transmission tunnel by way of a "conceptually brilliant" five-speed indirect gearbox designed by Richard Ansdale and Harry Mundy, which suffered from a (long-undiagnosed) problem of slinging oil away from its gears. It also introduced a rear suspension with what came to be called "Chapman struts", essentially a MacPherson strut with universal joints as suspension pieces. This was well suited to a space frame chassis, and may have inspired Chapman, always obsessed with reducing weight, to try it.
This was the first Lotus to be fitted with the iconic wobbly-web wheels. Reflecting Chapman's emphasis on engineering, these were magnesium, a kind of crimped cylinder, resulting in minimum material and maximum strength, without the weaknesses induced by slots in conventional rims. Despite its engineering advances, the 12 was not a success in F1. In F2, the car won the class in the mixed F1/F2 1958 BRDC International Trophy, driven by Cliff Allison, but in spite of a small number of podiums, was usually drowned in a sea of Coopers.