1950 Jaguar XK120
1950 Jaguar XK120
Photo: Bill Vance

by Bill Vance

Although many different British sports cars arrived here in the 1950s, two makes can really be credited with establishing the sports car market in North America following the Second World War: MG and Jaguar. Specifically, these were the MG TD and the Jaguar XK120.

Jaguar had built sports roadsters before the war, most notably the SS-100, later the Jaguar 100, but felt that a new post-war car was needed. Chief engineer William Heynes designed the mechanical components, while company co-founder William Lyons did the styling. Although not a trained auto stylist, he had an uncanny appreciation for grace and beauty.

The engineering design parameters were quite daring. The engine was to develop peak power at a high 5000 rpm, and have double overhead camshafts, a feature heretofore used almost exclusively in racing cars.

Heynes came up with a 3.4 litre inline six with a massive crankshaft running in seven large main bearings. It had a surprisingly long stroke for a post-war engine (bore and stroke were 83 by 106 mm (3.27 by 4.17 in.). Peak horsepower was 160 at 5200 rpm.

This double overhead cam six had been intended to power a Jaguar sedan. When the engine was completed it was installed in the roadster as a temporary test bed while the sedan was being readied. The XK120 roadster, as it was called, proved so overwhelmingly popular that it was continued. The big sedan for which the engine was originally intended would arrive in 1951 as the Jaguar Mark VII.

In styling the roadster Lyons created a long, sensuously flowing hood and fender line with the headlamps nestled between the hood and fenders. He used a delicate vertical bar grille with light bumpers, and rear fender skirts that provided a continuity of line the full length of the car, although they couldn’t be used with wire wheels and knock-off hubs.

When the new XK120 Jaguar was introduced at Earls Court, rotating on a tilted platform, its impact on the crowd was electric. The motoring world was stunned. Not only was it graceful and lithe, its 160 horsepower, twin-cam engine also promised to achieve the 120 mph that inspired its name. And the new Jaguar was priced at a modest 1,275 pounds sterling, a figure so low that sceptics predicted it would never come to market for that, if it came at all.

Lyons and Heynes quickly capitalized on the favourable reception. In May, 1949, they took an XK to the famous Jabbeke highway in Belgium to prove its performance. Fitted with an underpan and tonneau cover, and without a windshield, the XK120 achieved a top speed of 132.6 mph (213 km/h), making it the world’s fastest production car. In standard road trim it managed 126 (203).

To prove that the XK had durability as well as speed, Heynes developed a racing version, the XK120C (for “competition”). A three-car team of Cs was entered in the 1951 Le Mans 24-hour endurance race in France. One of them won the event at an average speed of 93.49 mph (150 km/h), the first of five Jaguar victories at Le Mans in seven years.

A final feat of durability was performed in 1952 by an XK120 coupe (introduced in 1951) on a track in Montlhery, France. A team of crack racing drivers, including a young Stirling Moss, pounded the Jaguar around the Montlhery circuit for seven solid days and nights. By week’s end it had covered 27,148 km (16,862 miles, and averaged 161 km/h (100.31 mph), a truly remarkable demonstration of mechanical endurance.

When the XK120 arrived in North America, it was equally impressive. Road & Track magazine (5/51) reported a top speed average of 121.6 mph (196 km/h), and a zero to 60 mph (96 km/h) time of 10.1 seconds. Tom McCahill of Mechanix Illustrated recorded zero-to-60 (96) in 9.0 seconds and a top speed of about 122 mph (196 km/h). He said the Jag rode “like a bubble in a wash basin.”

There were, however, some quality problems, and the ever forthright Tom reported them too. He called it “A rather crudely assembled job…put together like a Chinese laundryman’s version of a western sandwich.” In summarizing its assembly, Tom concluded that “it would have been better if they had just shovelled the unassembled parts of the car I drove into an old bag and shipped them over parcel post.”

But in spite of this, Tom was enthraled by the Jaguar and called it the finest high speed touring car in the world, lavish praise indeed.

Although meant for touring only, the XK was raced and rallied, and scored many victories. Brakes were its greatest competition weakness; they were prone to early fading under hard use. Its steering was also quite heavy, although front torsion bars contributed to quite good handing.

In spite of some shortcomings, the XK120 Jaguar combined stupendous performance, stunning beauty and a relatively reasonable price of under $5,000. During its model run from 1949 to 1954, when it was replaced by the XK140, 7,630 roadsters, 2,678 coupes, and 1,769 convertibles were produced. It is one of the benchmark cars in automotive history.

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