The first public demonstration of the sports-car's performance on that closed superhighway near Jabbeke in Belgium in 1949 was devoted to proving the promise, and the stripped-down 120 actually went 132-plus on that occasion.
That was with the original 160-horsepower twincam XK six-cylinder engine. Four years later, in April 1953, a 180-horsepower XK 120 roadster equipped with bellypan and small wind-screen demonstrated an impressive 141.8 mph at Jabbeke. The same car returned the following October, albeit much more highly modified, and test driver Norman Dewis vaulted it to the astonishing velocity of 172.4 mph.
This astounded even Jaguar's own people; privately, they admitted they'd have been happy with 155.
But on hand that same day was another Jaguar that went 178.3 mph. This one was a virtual streamliner, a very small, very smooth egg-shaped car whose single driver's seat was capped by a tiny plastic bubble taken from a sailplane. It was even more advanced under its eggshell, for the chassis was not a steel-tube space-frame, as on the C-Type, but a stressed-skin structure, or mono-coque largely made of magnesium sheetmetal.
Though never formally announced as such, there were enough rumors and, subsequently, official evidence, to be sure this car had originally been intended for the 1953 LeMans race.
But it is just as clear that Jaguar's sour experience of 1952, when the "droop-snoot" C-Type body was rushed to race without sufficient testing, led to second thoughts about this new experimental design. It thus stayed at the factory, deemed either unready or in some other way unsuitable for the 1953 event.
But as often happens with such cars, it was pressed into service as a research vehicle and covered many thousands of miles on various test tracks before finally being revealed at Jabbeke in streamliner form. We can also be sure that it greatly helped Heynes and company in designing what did appear as their next LeMans car.
One other interesting prototype was secretly built and tested in this period, though it was more of an unofficial sideline and led to less. William Lyons, whose company was basically founded on his sense of style, was always experimenting in full-scale with various body ideas.
Possibly to help himself come to grips with true streamlining, a big change from the more traditional forms he'd long since mastered, he spent much of 1953 playing with a vehicle along the lines of a racing sports car like the C-Type.
Looking very aerodynamic, it had a low, rounded nose and a sleek, unbroken torpedo profile leading to a tapering tail. All four wheel openings were enclosed with spats ("valences" in Jaguar parlance), and the driver sat behind a small cowl and curved plastic aeroscreen. So far, so avant garde. And indeed, tests carried out by Dewis that September indicated drag was about 15 percent less than the contemporary C-Type's.
By that stage, Lyons seemed to have been thinking of setting some sort of speed record with his hobby car, for one of the tests involved filling the rear axle with soap as a low-drag lubricant. The project was soon abandoned.
The prototype was an interesting sideline, but unfortunately the overall visual impression was of a very ungainly contraption, with tall and wide fender lines giving a thick-in-the-middle look, and a seat mounted so high that the driver stuck out comically. Around the factory, Lyons' strange beast was known variously as "Bronco" or "The Brontosaurus." It was probably the ugliest thing he ever did.
No, the correct path toward the future was shown by Heynes' speedy-looking magnesium egg. Out of it in the spring of 1954 emerged the immortal D-Type.
For more on Jaguar and other great cars, see:
- Jaguar Cars: Check out more information on the great sporting cars.
- How Sports Cars Work: Get the lowdown on hundreds of fantastic sports cars from the 1940s to today.
- Classic Cars: Learn about the world's most coveted automobiles in these illustrated profiles.
- Ferrari: Learn about every significant Ferrari road car and racing car.
- New Jaguars: Reviews, ratings, prices, and specifications on the current Jaguar lineup from the auto editors of Consumer Guide.
- Used Jaguars: Reviews, recalls, trouble spots, and more on pre-owned Jaguars starting with the 1990 model year. From the auto editors of Consumer Guide.