Jaguar XK120
The world's fastest production car at its 1948 debut.
The Jaguar XK120, built from 1948 to 1954, marked Jaguar’s return to sports cars after the SS 100 ceased production in 1939. It first appeared at the 1948 London Motor Show as an open two-seater roadster, intended as a testbed for the new XK engine designed by chief engineer William Heynes. The car created such a stir that Jaguar’s founder and chairman, William Lyons, decided to put it into series production. At its debut, it held the title of the world’s fastest production car.
The first 242 cars, hand-assembled between late 1948 and early 1950, featured aluminum panels over an ash wood frame. From early 1950, production switched to heavier all-steel bodies, adding about 112 pounds. The “120” in its name referred to the aluminum car’s top speed of 120 mph—faster still with the windscreen removed—making it the fastest production car available at launch. The first production example, chassis number 670003, went to actor Clark Gable in 1949.
Three body styles were offered, all two-seaters, in both left- and right-hand drive: an open two-seater (called a roadster in the US), a fixed-head coupé from 1951, and a drophead coupé from 1953. A small run of Special Equipment roadsters and fixed-head coupés, marked with an ‘S’ before the chassis number, were sold to enthusiasts between 1948 and 1949. A planned version with a 2-liter four-cylinder engine, the XK100 for the UK market, was canceled before production began.
On May 30, 1949, on the Ostend-Jabbeke motorway in Belgium, a prototype XK120 timed by the Royal Automobile Club of Belgium averaged 132.6 mph in two opposing runs, using only a small aero screen and an optional taller top gear. With a passenger-side tonneau cover, it reached 135 mph. In 1950 and 1951, at the Autodrome de Linas-Montlhéry in France, open XK120s averaged over 100 mph for 24 hours and over 130 mph for an hour. In 1952, a fixed-head coupé set multiple world speed and distance records, averaging 100 mph for a full week. The model also achieved notable success in racing and rallying.
At auction in 2016, Bonhams sold a matching-numbers, left-hand-drive alloy-bodied roadster—one of only 184—for $396,000 (£302,566), the highest price ever paid for an XK120.
The XK120’s steel chassis borrowed heavily from the Jaguar Mark V, using many of the same components.
Quick Facts
- Manufacturer
- Jaguar Cars
- Production
- 1948–1954 / 12,055 made
- Class
- Sports car
- Predecessor
- SS Jaguar 100
- Successor
- Jaguar XK140
- Assembly
- United Kingdom: Holbrook Lane, Coventry (1948–1951) / United Kingdom: Browns Lane, Coventry (1951–1954)
- Related
- Jaguar C-Type
- Layout
- FR layout
- Engine
- 3.4 L XK I6
- Transmission
- 4-speed manual
- Wheelbase
- 102 in
- Length
- 173 in
Facts from the source article.
Lore & Background
The XK120 was developed around the new XK engine designed by Jaguar Chief Engineer William Heynes. The first 242 cars were hand-built with aluminium panels on ash wood framing; production switched to heavier all-steel bodies in early 1950. The '120' in the name referred to the aluminium car's 120 mph top speed, which made it the world's fastest production car at launch. Three body styles were offered: an open two-seater (roadster), a fixed head coupé from 1951, and a drophead coupé from 1953. A version with a smaller 2-litre 4-cylinder engine designated the XK100 was cancelled prior to production.
On 30 May 1949, a prototype XK120 timed on the Ostend-Jabbeke motorway in Belgium achieved an average of 132.6 mph with a small aero screen and a catalogued alternative top gear ratio, and 135 mph with a passenger-side tonneau cover. In 1950 and 1951, at Autodrome de Linas-Montlhéry, open XK120s averaged over 100 mph for 24 hours and over 130 mph for an hour. In 1952 a fixed-head coupé averaged 100 mph for a week, taking numerous world records. The XK120 was also highly successful in racing and rallying.
The open two-seater provided little weather protection, with a lightweight folding canvas top and detachable sidescreens. The drophead coupé had a padded, lined canvas top and roll-up windows. All models had removable spats covering the rear wheel arches. The Special Equipment version offered increased power, stiffer suspension and a dual exhaust system. The XK engine's basic design, later modified into 3.8 and 4.2-litre versions, survived until 1992.
Reader's Guide
The Jaguar XK120 established Jaguar as a manufacturer of high-performance sports cars after World War II. Its debut at the 1948 London Motor Show as a show car caused such a sensation that it was put into production, becoming the fastest production car in the world at that time. The XK120's advanced dual overhead-cam XK engine, designed by William Heynes, set a benchmark for mass-produced engines and remained in production in various forms until 1992. The car's success in racing and rallying, including its first race victory at Silverstone in 1949 and class wins in America, demonstrated its performance and durability. The XK120's design and engineering directly led to the XK140 and XK150 models. Its combination of speed, style, and relative affordability made it a landmark vehicle. In 2016, a matching-numbers alloy-bodied roadster sold at auction for $396,000, the highest price achieved for an XK120 at that time, reflecting its enduring collector status.
Did You Know?
- The first production XK120, chassis number 670003, was delivered to actor Clark Gable.
- The first 242 XK120s had aluminium bodies on ash wood framing; later cars used pressed-steel bodies.
- A prototype XK120 averaged 132.6 mph on the Ostend-Jabbeke motorway in Belgium in 1949.
- The XK120's engine design survived until 1992, later modified into 3.8 and 4.2-litre versions.
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