The 1922 Lancia Lambda is widely recognized as the first production automobile with a unitary body and chassis.
Designed by Vincenzo Lancia and engineer Battista Falchetto, the Lambda replaced a separate body-on-frame layout with a load-bearing steel structure. Its design also used an unusually low floor and independent front suspension, features that improved both handling and passenger comfort.
The Lambda was produced in multiple series from 1922 to 1931. It was not the first vehicle ever to experiment with a unitary structure, but it was among the first to make the concept a successful production reality. This distinction is why it is often cited in automobile histories as a landmark in modern body engineering.
A common mix-up is to credit the Citroën Traction Avant, introduced in 1934. That car was highly influential for combining front-wheel drive, unitary construction, and other advanced features, but it came more than a decade after the Lambda.