|Produced tot.:||7614 units|
|Colour:||Old English White|
|Engine:||3,4 l XK, R6|
|Engine capacity:||3442 cm³|
|Power:||162 hp at 5000 rev.|
|Max. speed:||200 km/h|
|Dynamics:||0-100 km/h – 10 s|
|Average fuel consumption:||14,3 l/100 km|
|Dead weight:||1320 kg|
|Notes:||First registration commenced in USA.|
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 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.
The XK120 was ultimately available in two open versions, first as an open 2-seater described in the US market as the roadster (and designated OTS, for open two-seater, in America), then also as a drophead coupé (DHC) from 1953; and also as a closed, or fixed head coupé (FHC) from 1951.
A smaller-engined version 2-litres, 4 cylinders, intended for the UK market was cancelled prior to production.
On 30 May 1949, on the empty Ostend-Jabbeke motorway in Belgium, a prototype XK120 timed by the officials of the Royal Automobile Club of Belgium achieved an average of runs in opposing directions of 132.6 mph with the windscreen replaced by just one small aeroscreen and a catalogued alternative top gear ratio, and 135 mph with a passenger-side tonneau cover in place. In 1950 and 1951, at a banked oval track in France, XK120 roadsters averaged over 100 mph for 24 hours and over 130 mph for an hour, and in 1952 a fixed-head coupé took numerous world records for speed and distance when it averaged 100 mph for a week.
Roadsters were also successful in racing and rallying.
The first roadsters, hand-built with aluminium bodies on ash frames mounted on modified Jaguar Mark V chassis, were constructed between late 1948 and early 1950. To meet demand, and beginning with the 1950 model year, all subsequent XK120s were mass-produced with pressed-steel bodies. They retained aluminium doors, bonnet, and boot lid. The DHC and FHC versions, more luxuriously appointed than the roadsters, had wind-up windows and also wood veneers on the dashboard and interior door caps.
With alloy cylinder head, hemi-spherical combustion chambers, inclined valves and twin side-draft SU carburetors, the dual overhead-cam 3.4 L straight-6 XK engine was comparatively advanced for a mass-produced unit of the time. With standard 8:1 compression ratio it developed 160 bhp (119 kW), using 80 octane fuel. Most of the early cars were exported; a 7:1 low-compression version, with consequently reduced performance, was reserved for the UK market, where the post-war austerity measures then in force restricted buyers to 70 octane "Pool petrol". The Jaguar factory, with access to 80 octane fuel, provided roadsters with the higher compression ratio to the press. Journalists could then test the model's optimum performance in Belgium, on a long, straight stretch of road between Jabbeke and Ostend. The XK engine's basic design, later modified into 3.8 and 4.2 litre versions, survived into the late 1980s.
All XK120s had independent torsion bar front suspension, semi-elliptic leaf springs at the rear, recirculating ball steering, telescopically adjustable steering column, and all-round 12 inch drum brakes that were prone to fade. Some cars were fitted with Alfin (ALuminium FINned) brake drums to help overcome the fade.
The roadster's lightweight canvas top and detachable sidescreens stowed out of sight behind the seats, and its barchetta-style doors had no external handles; instead there was an interior pull-cord which was accessible through a flap in the sidescreens when the weather equipment was in place. The windscreen could be removed for aeroscreens to be fitted.
The drophead coupé (DHC) had a padded, lined canvas top, which folded onto the rear deck behind the seats when retracted, and roll-up windows with opening quarter lights. The flat glass two-piece windscreen was set in a steel frame that was integrated with the body and painted the same colour.