Journal: The XK120 Fathered the British Supercar

The XK120 Fathered the British Supercar

By Alan Franklin
June 27, 2013

One hundred and twenty miles per hour isn’t all that impressive a top speed in 2013, really, It wasn’t even all that impressive 20 years ago. Today, even bare-bones economy trolleys are usually capable of this speed, as I may or may not have recently confirmed through abuse of a rented Chevy Sonic. In late 1940s England, however, the only way one could travel at two miles a minute while remaining on the ground was by land speed record steam locomotive, as typical day-to-day cars of the era were lucky to touch 80 MPH downhill and with a stiff tailwind. Things would change very soon.

Designed in the thick of WWII, Jaguar’s XK series straight six was literally drafted in between bomb fire watching shifts, the engineers responsible for its advanced design also tasked with keeping an eye out for incoming German bombers. Initially displacing 3,442 CCs and developing a healthy 160 horsepower, the XK was among the first production engines built with both dual overhead cams and hemispherical combustions chambers. Autocratic managing director Sir William Lyons dictated that this new motor “must look good” as well, and as a man who was used to having his way, we can’t imagine he was disappointed with the end results—the XK remains one of the prettiest engines of any configuration ever sold. They sound flipping excellent too, and the fact they remained in production for more than 40 years is a testament to its inherit “rightness” of design and construction.

First shown on a stand at the 1948 London Motor Show in roadster form, and ostensibly as merely a showcase for this advanced new engine, the XK120 absolutely stunned the gathered crowds. This overwhelmingly positive response “convinced” Lyons to put it into production, though it’s no secret he’d been wanting a new sports car for Jaguar ever since the demise of the SS 100, which had ceased production at the onset of war nearly a decade earlier. In keeping with its predecessor, the last three numbers of the XK120’s name denoted its terminal velocity.

Shortly after its successful reveal, the XK120 entered serial production, with the first 242 examples being hand-bodied in aluminum over ash framing mounted to a modified Mark V saloon chassis—later cars would switch to conventional steel for ease of manufacture, but retained the earlier car’s lightweight opening panels. DHC and FHC versions, their abbreviations meaning “drophead coupe” and “fixed-head coupe”, respectively, were more luxurious alternatives to the stripped-out and racer-ish roadster, replacing that car’s plastic sidescreens with rolling glass windows in addition to cabins trimmed with wood veneers. Spats, or skirts as we call them in The States, were fitted as standard, though easily and frequently removed by owners.

Returning again to that magic three digit figure, the XK was so far ahead of its competitors in terms of performance, design, and engineering it may have well been from the future. With an as-released cost of £998, it was also shockingly affordable, though obviously still far out of reach for most. The 120’s incredible turn of speed and glamorous looks were further helped by shrewd marketing, with the first production roadster being delivered to Clark Gable, not to mention the reputation it earned in countless motorsport victories across several continents in many forms of racing.

Throughout the years the XK would be modified with more power and correspondingly higher numbers in its name, but unfortunately each new partial redesign came with a host of less successful styling “improvements” in the way of more chrome, more detailing, more visual fuss. I for one prefer to remember the series for the early 120 roadsters, though, preferably in white or silver, these unassuming hues helping to highlight the car’s minimal lines—somehow simultaneously flowing and static, an intriguing mix of sporty rakishness and staunch, upright simplicity no doubt influenced by the very large and very proper saloon cars more typical of Jaguar during the time. The E-type may be remembered more fondly among many, but to me, the original English supercar remains the best—every technologically advanced British sports car developed since carries a bit of its DNA.

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2 years ago

Having had 2 xk120 roadsters over the past 40 years, I still love to look over the flowing lines of my daily driver.. Many upgrades to make it more reliable including modern wiring, front disc brakes and engine electric fan.

Jose Delgadillo
Jose Delgadillo
6 years ago

I bought my 1951 mark VII so that I could experience the original XK motor. It is equipped with manual shift.

Matthew Lange
Matthew Lange
10 years ago

Personally think the prettiest of the XK120’s was the fixed head coupe. Has a great mix of 50’s styling mixed with pre war Bugatti about it. Jag changed the design for the XK140 FHC and while it allowed for more accommodation it is not as attractive.

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