The Jaguar XK120 is a sports car which was manufactured by Jaguar between 1948 and 1954. It was Jaguar's first sports car since the SS 100, which ceased production in 1940.
The XK120 was launched in open two-seater or (US) roadster form at the 1948 London Motor Show as a testbed and show car for the new Jaguar XK engine. The display car was the first prototype, chassis number 670001. It looked almost identical to the production cars except that the straight outer pillars of its windscreen would be curved on the production version. The roadster caused a sensation, which persuaded Jaguar founder and design boss William Lyons to put it into production.
Beginning in 1948, the first 242 cars wore wood-framed open 2-seater bodies with aluminium panels. Production switched to the 1cwt or 112 lb (51 kg) heavier all-steel in early 1950. The "120" in the name referred to the aluminium car's 120 mph (193 km/h) top speed (faster with the windscreen removed), which made it the world's fastest production car at the time of its launch. In 1949 the first production roadster, chassis number 670003, was delivered to Clark Gable.