All Jaguar 120's built between 1948 and 1950 (242 in total) were essentially hand built, with aluminum bodies on ash frames. The 120 was powered by the in-line six with dual overhead camshafts and twin side-draft SU carburetors. With standard compression (8:1) it developed 160 horsepower. That engine, with modifications, remained in production through 1987.
The 120 chassis featured independent torsion bar front suspension, leaf springs at the rear, recirculating ball steering, and front and rear drum brakes (that were prone to fade).