The Jaguar XK120 was the first sports car to be manufactured by Jaguar after the Second World War. It was in production between 1948 and 1954. It was one of the first cars to bring luxury into a sports car. It was launched in 1948 as a two-seater roadster. Later, in 1951, a fixed head coupe model was launched and a drop head coupe model was launched in 1951. It was to replace the jaguar SS 100 launched in 1936.

The car was designed by the Co-founder of Jaguar, Sir William Lyons. It was a revolutionary car at its time of launch to have combined touring car standards of comfort with sports car performance. It was priced lesser than its rivals, yet packing in performance that could exceed another production car of its time. It was the sort of car that could deliver race car like performance while lapped in luxury and a cockpit with wood inserts.

The XK120 was named so because of its top speed, 120mph. This made it the fastest standard production car in the world at the time of its launch. It has been officially timed at 136.596mph in 1949 by the Royal Automobile Club of Belgium. It was the first car to feature the Jaguar XK series engine, which was used for six decades powering Jaguar into various race victories. In 1951, an XK120C won the 24 hour Le Mans race held in France.

Though the first few hundred cars had all-aluminum body, the overwhelming demand and mass production compelled Jaguar to use pressed steel body on the XK120 coupled with the aluminum doors, boot lid and bonnet from 1950.

The straight 6 Dual Overhead cam XK engine featured twin side draft SU carburetors and alloy cylinder head. It displaced 3442 cc. Even with the standard compression ratio of 8:1, it produced 160 bhp. The more powerful SE versions produced 180 and 210bhps. It was one of the more advanced mass production car engines of its time. The modified versions of the same XK engine survived till late 1980s jaguars.

While the engine was powerful enough for racing, the disc brakes that came with all the four wheels used to fade with repeated use and the steering was too heavy and not responsive enough to make it the ultimate-racing car. But, Jaguar more than made up for this by launching the XK120C for competition purposes. As if the original XK120 was not enough, SE versions were made with more powerful engine, stiffer suspension more better handling and dual exhausts.

The roadster had canvas top that was detachable. The side screens too were detachable. A strange fact about the car was that it did not have any external door handles.

The XK120 was the first production car to top 100mph average speed on the 24 hour and 7days 7 nights endurance races in 1950 and 1952 respectively.

It was the XK120 that brought Jaguar to fame. It was the car that defined what a Jaguar should be, a luxury car that can deliver sports car levels of performance. Jaguar produced over 17,000 XK120s before its production was stopped in 1954. It was succeeded by the XK140 in 1945.