KWE: Introducing the Jaguar XJS
The Jaguar XJS (codenamed XJ27) design started around 1965 with the first production car being sold in 1975. It was primarily designed by Malcolm Sayer with input and control from Sir William Lyons. Although the public assumed the XJS was a successor to the very popular Jaguar E-Type it was in fact intended to be very different in that it would be comfortable and luxurious - less a sports car than a sports tourer. This allowed it to use the same suspension layout as the recently introduced and supremely cosseting Jaguar XJ6. Externally the Jaguar XJS is most noticeable for its 'flying buttresses' sweeping from the top of the rear roofline down to the rear of the wings. Some criticize this feature but in fact this was a common design for sports cars of the period such as Maserati and Ferrari. It also gave the quite large Jaguar XJS an excellent drag coefficient - better than the E Type and allowing the XJS easily to attain over 150mph.
The Jaguar XJS's engine was a fuel-injected version of the E-Type's 5.3 litre V12 - still one of the finest engines in the world today. It was thirsty though, and in 1981 the HE engine with modified cylinder head design and better ignition system was introduced which improved fuel consumption by over 20%. Transmission was the robust and smooth GM400 3 speed auto. The V12 auto remained in production for all the 21 years of the Jaguar XJS production history.
In 1983 Jaguar introduced a completely new 3.6 litre straight 6 engine with 4 valves per cylinder, intended to take over from the venerable 4.2 litre XK engine in the XJ6 saloon. It was successfully trialled in the Jaguar XJS, mated to a 5 speed Getrag manual gearbox. The reduced engine weight and 5 speed box made up for reduced power compared with the V12 and resulted in a better balanced car.
In response to demand mostly from America, a cabriolet body was introduced at the same time followed by the V12 cabriolet in 1985. This body lost the flying buttresses, had a folding rear canvas roof and removable hard roof panels at the front. The Jaguar XJS retained rigidity since there was a central transverse roof beam, and the strong roof gutter sections remained, running fore and aft.