Lancia produced the first production car with a monocoque-style chassis: the Lancia Lambda.
Introduced in 1922, the Lambda used a load-bearing body rather than placing a conventional body on a separate ladder frame. Its steel structure improved rigidity while allowing a lower, lighter design. Technically, it is often described as a partial monocoque or unitary body because its roof was not fully structural.
The Lambda was also notable for its independent front suspension, sliding-pillar design, and narrow-angle V4 engine. These features made it one of the most technically advanced cars of the 1920s.
A common mix-up is Citroën’s Traction Avant, launched in 1934. That model helped popularize unibody construction, but Lancia’s Lambda came first. The Lambda remained in production from 1922 to 1931 across 11 series.