Only five... Throughout Jaguar 75 year history, only five models of sports car have graced the company's showrooms and prowled roads around the world. That's not many and shows that Jaguar usually gets it right the first time with models that remain in production for long periods of time, needing only minor updates along the way... The Jaguar XK sports car is number two in this exclusive lineage and while its successor, the E-type, may be better known and more recognizable, the XK120 was as much a revolution when it was launched in 1948 offering performance and value no other manufacturer could match.

Immediately following World War Two, most of the offerings were still based on pre war designs; reconstruction and rationing in Britain meant that it took a few years for new designs to arrive on the market. Rationing was such that to get raw materials, especially steel, manufacturers had to export the bulk of their production, helping bringing in currencies in to the country.

William Lyons, Jaguar's founder, was keen to continue developing the company he had established some 20 years earlier and he quickly realized that it meant building his own engines instead of relying on an outside manufacturer like SS Jaguar had done until this point. With Bill Heynes leading a small team of engineers, including Wally Hassan and Harry Weslake, planning and development for Jaguar's new powerplant begun even before hostilities ended. Over some 3 or 4 years, a number of experimental engines were designed and tested starting with 4 cylinder models, code named X for experimental and followed by a sequence letter: XA, XB, etc... Each gaining a little more power toward the ultimate goal of 160 hp established by Lyons. In 1948, the current evolution was the XJ engine, a 4 cylinder, 2 liter, dual overhead cam, which developed a little under 150 hp. Interestingly, it was tested on the same stretch of highway in Jabbeke Belgium where a few months later, the XK120 would rewrite the record books for production cars. Installed in a special streamlined lightweight MG, the 4 cylinder engine pushed the purpose built car to a top speed of 175 mph but when installed and driven in a Mark V, Lyons felt it lacked the low end torque needed for the new Jaguar saloon. Back to the drawing board for a 6 cylinder, 3.4 liter version, named XK: Jaguar had the engine it needed to leap over its competition.

A rare 1949 XK120 alloy body roadster. Tony Hldebrand (South Florida Jaguar Club)