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1952 Jaguar XK120 Supersonic

Over the years, many automotive designs have been inspired by nautical vessels, aircraft, and spaceships. From the boattail speedsters of the 1920s to the tail fins of the 1950s, automobile designers have used the most efficient and dynamic design cues from various modes of transportation for design inspiration. When Giovanni Savonuzzi-penned the futuristic 'Supersonics,' his inspiration came from the jet age with thoughts of breaking sound barriers and stratospheres. The designs he created were comprised of contemporary and modern trends in aerospace and featured streamlined forms, subtle tail fins, and a swept-back roofline. The most efficient designs from the air were brought to the tarmac, in harmonious and graceful lines.

The radical design of the Supersonics was graceful, elegant, and slightly flamboyant. They were one of the first cars to feature designs that would later become known as 'jet-age' styling. The first Supersonic design appeared on a Conrero-tuned Alfa Romeo 1900 entered in the Mille Miglia during the early 1950s. The aluminum coachwork with streamlined curves was later emulated on a small run of Fiat 8V chassis (approximately eight examples), an Aston Martin, and at least three Jaguar XK120s.

The production body of the Jaguar XK120 was slippery, curvaceous, and (arguably) one of the most appealing of all time. Enzo Ferrari declared the XK120 'the most beautiful car ever made.' Replacing the standard body was no small task.

The Jaguar XK120

When Jaguar founder and Chairman William Lyons introduced the XK120 in 1948 at the London Motor Show, it caused such a sensation that it was quickly put into production. Between 1948 and 1950, the bodies were built from hand-formed lightweight aluminum alloy over an ash frame and were powered by a new 3,442cc double-overhead camshaft six-cylinder engine. The later steel-bodied XK120s sold in vast numbers and secured Jaguar's fine reputation as a major manufacturer of race and sports cars in the 1950s. In all, 10,309 XK 120 roadsters and coupes were built from 1949 to 1954.

The XK engine was designed by Jaguar Chief Engineer William Heynes. The dual-overhead-cam 3.4-liter straight-6 XK engine had twin side-draft SU carburetors, inclined valves, high-strength aluminum alloy cylinder head, and Hemispherical combustion chambers. With 8:1 compression, the engine developed 160 horsepower (the competition variant had 9:1 compression and produced upwards of 180 bhp). Most examples had 12-inch drum brakes although some received Alfin (ALuminium FINned) brake drums to help overcome brake fade. The suspension was a Heynes-designed torsion bar front setup with semi-elliptic leaf springs at the rear. Steering was by a recirculating ball with a telescopically adjustable steering column.

The Jaguar XK120 Supersonic by Ghia

At least three 'Supersonic' designs were bestowed upon one of the most advanced sports cars of the era, the Jaguar XK120. The aerodynamic design and lightweight aluminum construction were intended to enhance the performance of the XK120, and the futuristic styling was to be equally captivating.

Ghia created the coachwork and, in one example, specialist Virgilio Conrero removed the two SU carburetors from the engine and replaced them with three two-barrel Webers, boosting output to 220 brake horsepower. At least one example was shown at the Paris and London shows in 1954, and at the concours d'elegance competition in Montreux. All three Jaguar Supersonics were on display at the Cannes Concours d'Elegance.

At least two of the Jaguar XK120s, both left-hand-drive examples, were built to the order of Monsieur Malpelli, reportedly a businessman from Lyon. One of these two examples (chassis 679768) received engine modifications from Conrero. After Monsieur Malpelli failed to pay the bill for the Supersonics, the Parisian dealer Delecroix reclaimed them. At least one example remained with the dealer until 1969.

by Dan Vaughan

Coupe by Ghia
Chassis number: 679768
Engine number: W 5162-8

First produced in 1949, the XK120 featured legendary coachwork crafted by William Lyons. However, a few bare chassis were sent to outside coachworks and this car is one of three that went to Ghia for a 'supersonic' body. The advent of the jet age produced such icons as the tailfins on the 1959 Cadillac, and, in Europe, Giovanni Savonuzzi of Ghia created supersonic coachwork for the Alfa Romeo 1900, Aston Martin and Fiat 8V. This Supersonic Jaguar is one of two commissioned by Malpelli, and the only one ordered with a modified cylinder head to accommodate triple carburetors in place of the usual twin carburetor configuration. On completion, it was exhibited at auto shows in Paris and London and appeared at concours in Montreux and Cannes. One of two existing Supersonic Jaguars, this car was acquired by its current caretaker in 2015, and has been dutifully restored to its original livery.

The Jaguar XK120 was designed to be a prestigious vehicle and produced in low numbers. The designation '120' represented the vehicle's top speed of 120 miles-per-hour. At the time, it was the fastest production car in the world.

The British automotive industry was greatly influenced by World War II. Many manufacturers went out of business due to the lack of funds, fuel and supply shortages, or their factories had been destroyed during the war. In order to stay in business, a solid production line was required that could compete with its class of vehicles. William Lyons, the owner of Jaguar, did so by creating a new class - one that was faster, more reliable, stylish, and cheaper than any other vehicle on the market.

To gain industry recognition, Lyons knew that he needed a show car that was revolutionary and bold. Lyons handled the styling while his chief engineer, William Heynes, was tasked with designing the mechanical components. When the vehicle was displayed at Earls Court, the reaction was overwhelming. Originally, Lyons planned to make between 100 and 200 examples. After the public reaction to the car and to keep up with demand, he decided to change the body from hand-formed aluminum to all-steel construction.

The body of the car was reminiscent of the 'French Curves' produced by manufacturers such as Bugatti and Delahaye of the early 1930's and 1940's. They were created in three different body styles, roadster, fixed head, and drop head (convertible).

The vehicle was powered by a 160 horsepower, 3.4 liter, inline-six-cylinder engine. Peak horsepower was achieved at 5000 RPM. The 120-mph was the promised speed, the top speed of the vehicle was around 126-132 mph depending on the trim of the vehicle.

The vehicle was designed as a touring car. However, many of the vehicles were raced. Their main weaknesses were their drum brakes which wore quickly, and their steering which was heavy and less responsive when compared to other purpose-built racing vehicles.

In 1951, Jaguar entered the grueling 24-hour of Le Mans endurance race. Three XK120C, the 'C' representing 'competition', was entered. One of the three entrants won the event.

In 1952, an XK120 was driven continuously for seven days and nights around a track located in Montlhery, France. After more than 16,000 miles in one week, the vehicle once again proved its endurance capabilities.

In 1954 production ceased. Over 12,000 examples were produced.

by Dan Vaughan