The Jaguar XJ-S
A New Breed of Cat
A new Jaguar model is a rarity, every one a landmark in motoring history. Styling has met with world-wide acclaim, performance has been something for other manufacturers to aim at. In performance and road manners the new XJ-S, a 154 m.p.h. sports coupe powered by the fuel-injected version of Jaguar’s V12 engine and using modified XJ saloon suspension, represents yet another pinnacle of achievement for the Big Cat, but in this writer’s opinion its styling is a disappointment. There is none of that breathtaking beauty which astounded the world on the introduction of the XK120 and the E-type. It resembles the proverbial bitza, a committee design, a bit of Ferrari-Dino in the curved, heavily-buttressed rear window, a bit of this and a bit of that, but less of the smooth, flowing, graceful lines for which Jaguar have always been admired. That the late, legendary aerodynamicist Malcolm Sayer, stylist of the C-type, D-type and E-type and the retired Sir William Lyons should each leave the XJ-S as his last styling monument is sad. One can only assume that Sayer’s original design produced shortly before his untimely death in 1970 was much more handsome before the adoption of US impact bumpers and the removal of his intended flip-up headlamps.
Still, aesthetic appreciation is a personal thing; it will doubtless grow on me. Undoubtedly it is distinctive enough to attract the people prepared to pay £8,900 for the most exclusive Jaguar ever. Only 60 per week will be produced, 75% of which are intended for the North American market, the rest for EEC countries and Australia. Jaguar emphasise that the XJ-S is not a replacement for the E-type: “The 12-cylinder E-type roadster marks the last of the line of that type of car which started with the XK in 1948 and continued with the E-type in 1961. These were trendsetters in their way and we hope that the XJ-S is also a trendsetter,” Keith Hopkins, Director of Sales and Marketing, British Leyland Cars, told us at the car’s introduction.
British Leyland believe that even in a time of economic restraint there remains a genuine and strong world market for this type of exclusive, exotic car — apart from the traditional buyers of exotica they hope to attract the wealthy who would normally steer clear of low volume exotics because of the lack of a good back-up system, a virtue which Jaguar claim on a world-wide basis.
Competitors? “There’s no real competition, no car on the market that has the same collection of virtues at such a competitive price,” was Keith Hopkins’ powerful boast. But in Jaguar’s book the Mercedes 450SLC is the closest rival at £11,271, the reason for the XJ-S’s introduction at the Frankfurt Show, a true gauntlet-throwing move. “The two cars weigh about the same and are about the same size, but the XJ-S has more luggage space, infinitely superior performance and, we believe, a style and a shape which Mercedes does not offer.”
Hopkins went on to claim that the XJ-S is one of the quietest if not the quietest sports car in the world. “There are some mid-engined cars which give higher G-forces in cornering, but get them on a normal, bumpy, cambered road and the XJ-S will pull away.” By the way, that overused “S” suffix, replacing the drawing office type number XJ27 by which we’ve known the car for the last couple of years, stands primarily for “Special”, but in best “Grace, Space and Pace” tradition Jaguar have invented the “Five Ss”: Style/Silence/Safety/Strength/Speed.
There is no doubt about the “Speed”. As well as producing a 154 m.p.h. maximum, that silken V12 will take this 33 cwt. machine to 60 m.p.h. from rest in 6.8 sec. and in conjunction with the Girling disc brakes, accelerate from zero to 100 m.p.h. and back again in just over 20 sec.
Description
The Body
The all-steel, monocoque, two-door, four-seater body is totally new yet is based upon the short-wheelbase (108.8 in.) XJ saloon/coupe floor pan. By moving the rear axle further under the saloon/coupe rear seat pan the wheelbase of the XJ-S has been reduced to 102 in. The track remains the same as for the saloons: 58 in. front, 58.60 in. rear. At 191.72 in. the XJ-S is an inch longer than the short-wheelbase XJ saloon and coupe and 3 in. shorter than the current I.w.b. saloon. Its width of 70.6 in. is nearly an inch more than the other XJ models and its height, 49.65 in., is 4.45 in. less. All current safety regulations and forthcoming North American and European regulations are met by the body design.
These bodies are produced on new tooling and press shop equipment at British Leyland’s Castle Bromwich plant and primed before delivery to Jaguar’s Allesley factory. At Allesley a new 2,000 ft. assembly line, unique to the XJ-S, has been installed alongside the XJ saloon and coupé lines, part of a £6.5 million investment for developing and producing this low volume car. Readers can judge for themselves from the photographs the styling features of the car. Most prominent are the wrap-around front and rear bumpers consisting of synthetic rubber-covered steel armatures mounted on Menasco struts, designed to meet the 5-m.p.h. U.S bumper regulations. These have since been withdrawn, but the bumpers have been retained for all XJ-Ss. The struts contain synthetic wax which, after impact, forces back the struts and bumpers to their original positions within 30 minutes.
Throughout development Sayer’s “slippery” aerodynamic design was harnessed, as he intended it to be, to contribute to road-holding and stability. As an adjunct to his basic design, Jaguar engineers added a spoiler and an undershield resulting in the MIRA wind-tunnels in a 50% reduction in the tendency of the car to lift and 10% less drag. The spoiler also reduced aerodynamic side forces and moved the centre of pressure rearwards as an aid to stability. All of which sounds impressive at it comes out of the Press Release, but the frank Bob Knight, Jaguar’s Director of Engineering, told us that in fact the air-dam had proved disappointing aerodynamically, but had been retained because it had a big effect on high speed cooling, helping radiator air throughput.
A laminated front screen is standard, together with tinted glass all round. There is electric window operation and the rear screen is heated. The doors, fitted with side-intrusion members, have a central, electrically-operated locking mechanism as on the Series 2 XJ saloons and likewise not including the boot lid. The big, forward-hinged bonnet is self-supporting on gas-filled struts and released and locked (to avoid slamming) by an interior lever.
As befits what is obviously likely to be one of the finest Grand Touring cars in the world, the XJ-S has a sizeable boot, equal to that of the XJ saloons, A new 20-gallon squab fuel tank across the back of the rear seat helps give a wide margin to meet the American 30 m.p.h. rear impact test. The spare wheel, complete with tailored cover, is mounted upright behind the tank. Within the black carpet-trimmed boot also are a sump tank below the main fuel tank, which provides a continuous supply of fuel to the high pressure fuel pump, thus preventing surge, the scourge of fuel-injection, the Lucas-made control unit for the Bosch injection and the Lucas Pacemaker battery, safe from that underbonnet heat which forces the use of a battery fan on the V12 saloons. As if to prove Jaguar attention to detail there are flap valves in the boot to remove stale air.
Noticeable features of the body styling are the Cibie quartz halogen biode headlamps designed specially for this car, a complex exercise because a the optical distortion of the aerodynamic shape. Each headlamp contains two independent reflectors, each equipped with a halogen H1 bulb for dip and main-beam functions, both of which work on main beam. The patented new optical structure comprises a screen of auxiliary prisms on a transparent sheet inside the main reflector. The screen pre-forms the beam and forms the cut-off at the top of the dip beam. The external lens carries additional prisms to finally distribute the beam pattern. These immensely powerful headlamps are replaced by twin, round “glow-worm” (as Bob Knight puts it) headlamps for the US market, which thus gets what its ridiculous regulations deserve.
Another novelty is the mounting of the two-speed, plus single-wipe facility, wiper motor and linkages as a single unit beneath the windscreen scuttle air vent. Undoing four screws enables the complete unit to be lifted out for servicing, so simple it’s amazing it has taken so long to be designed.
The Interior
It’s perhaps stretching it a bit for Jaguar to claim that four adults can travel in comfort, at least for long distances. The interior length is 5 in. shorter than that of the short-wheelbase XJ saloon, with an obvious effect upon rear-seat leg-room. But if the driver is prepared to sacrifice leg room then indeed four adults can be carried, width and head-room adequate enough in the rear to allow this. The front bucket seats are fully adjustable fore and aft, fully reclining and of a new design with the seat cushion made up of two separate components, the centre section and the outer square. The idea is that the centre gives under the weight of the occupant while the outer part grips firmly without pinching. The individual back seats are similarly designed. Thin front-seat backrests, made to help rear leg-room, have built-in adjustable headrests. Inertia reel belts (centre of a new safety controversy) are hidden neatly behind trim panels and a pair is optionally available for the rear seats too.
Interior trimming is almost typically Jaguar: Connolly leather, thick carpeting, but not a trace of wood veneer to be seen. The centre console is straight from the XJ6, with clock and auxiliary switches in the top part, and lower down window and door lock switches, arm-rest/locker, ash trays; gear-lever, twin switches for the Delanair automatic air-conditioning and Radiomobile push-button radio. Both these last items are included in the totally comprehensive standard specification, as is an electric aerial.
The full-width, vacuum-formed facia has lost the sumptuousness of previous Jaguars, has a large, lockable glove-box in which is a flip-up vanity mirror and contains all the instruments in a single nacelle ahead of the driver. No less than 18 warning lights are included along the top of the nacelle informing the driver of just about every blooming thing except that a wheel has dropped off, although there is a major fault warning light ordering the driver to stop the car and investigate. Between the 160 m.p.h. speedometer and tachometer are a brand-new type of auxiliary instrument, indicating water temperature, oil pressure, fuel content and battery condition. Known as vertical (the direction of the scale) “air-cored” units, they work by a variation in a magnetic field between two points, Move in the same plane so are easy to read and are said to give instant and accurate response to changing conditions.
A 15 1/2 in. (the same size as that of the latest saloons), leather-bound, acrylic steering wheel has XJ saloon column switches for lights and wipers on either side. There are no less than five interior lights in the cockpit. The handbrake lever is back to the old Mk. 1 and 2 saloon position on the outside of the driver’s seat, but that old business of getting the lever stuck up your trouser leg or wherever is obviated by a device which allows the lever to he pushed back into the off position once it has been applied. The brake is subsequently released by pulling up the lever and pressing the release button.
The Engine and Transmission
We described the new fuel-injected version of the 60 degree V12 Jaguar engine briefly in our August issue road test of the XJ 5.3 Coupé. The unit used in the XJ-S is absolutely identical, producing 285 b.h.p. DIN at 5,500 r.p.m.,(perhaps rounded off for publication — Harry Mundy, Jaguar’s Associate Director, Chief Engineer, Power Units, spoke of 287 bhp. at 5,750 r.p.m.) and 294 lb. ft. torque DIN at 3,500 r.p.m. Peak torque is a couple of lb. ft. down on the old carburetter engine, but is spread over a much wider, useful band. As always this 5,343 c.c., all-aluminium engine has a 90 mm. bore and 70 mm. stroke, a single overhead camshaft per bank and seven main bearings. It runs on a compression ratio of 9:1. The ignition is controlled by the Lucas Opus Mk. II electronic system.
Harry Mundy parried anticipated questions as to why Jaguar have chosen Bosch D-Jetronic electronic fuel injection (made under licence by Lucas) when Bosch have progressed through the later K-Jetronic to the new L-Jetronic. “We were way down the road with D-Jetronic when K-Jetronic — then a product of the Bosch Diesel division — was announced. D-Jetronic worked in our application and is well proved, with over three million car sets produced. The D gives a natural progression to the L.” Mundy pointed out that the V12 was conceived from the outset for fuel injection: “We went way down the road with Brico, who later withdrew, so we were some time getting under way again with injection.”
Apart from the improved “driveability” and tamper-proof virtues of the injected engine referred to in our XJ 5.3C road test, Mundy cited American Federal fuel tests carried out in 1974 on a fixed highway cycle which saw the carburetter V12 give 12.0 miles per US gallon. the injection car improve to 17.4 m.p.USg. and a BMW 3.0 injection give 15 m.p.USg.
Ancillaries to the engine include a Marston Superpak crossflow radiator, an oil cooler, an engine-driven viscous cooling fan and a thermostatically-controlled electric fan and stainless steel exhaust systems.
The XJ-S follows V12 E-type practice in being available with a choice of Borg-Warner Model 12 3-speed automatic gearbox or a 4-speed, all synchromesh manual gearbox (the V12 saloon and coupe is automatic only). Both versions use a Salisbury Powr-Lok limited slip differential with the 3.07:1 final drive ratio recently adopted by the XJ 5.3C. A single-piece propshaft is fitted. The manual gearbox has the latest revised ratios with slightly lower first gear. Informing us that the empty eighteenth hole in the dashboard illuminations might be utilised for an overdrive, Bob Knight confirmed what we’d suspected: Jaguar are working on an electrically controlled two-speed axle as an option for the car. A much more satisfactory and simpler answer might be to put into production the superb 5-speed gearbox we tried in Harry Mundy’s XJ12 recently (Motor Sport, August).
Running Gear
Most of the subframe-mounted suspension parts are identical to those introduced on the XJ6 in 1968, but the mountings, geometry and steering rack specification have been aimed at producing a more sporting steering response. At the front the semi-trailing wishbone and coil-spring suspension, with built-in anti-dive geometry, is retained, but the caster and camber angles have been modified and a thicker anti-roll bar of 0.875 in. diameter fitted. At the rear there are the familiar tubular lower transverse wishbones with driveshafts acting as upper links, radius arms and twin coil-spring damper units, much as first used on the E-type in 1961. To improve the roll stiffness for that sporting response a rear anti-roll bar of 0.75 in. has been fitted; the saloon has none, at least for the moment. Front and rear spring rates are slightly reduced to compensate for the reduced weight and improved roll stiffness compared with the V12 saloon.
Adwest power-steering is standard, of course. In the XJ-S the system is in its higher ratio guise, with an eight instead of seven tooth pinion and a 17.5:1 overall ratio, identical to the rack used in the XJ 5.3C.
Hand in glove with the suspension modifications goes a brand-new Dunlop tyre developed specially for the XJ-S. The 205/70 VR 15 in. Dunlop SP Super is a low profile, steel braced radial with a block tread pattern, which Bob Knight told us gives a much better wet grip and a better combination of traction and cornering forces. This tread reduces the degenerating bending forces in the tyre and so allows the use of a softer compound with much better damping to improve wet grip. Most of the high-speed endurance tyre testing was carried out on that favourite old jaguar stamping ground, the Jabbeke autoroute in Belgium. The tyres are fitted to the same, handsome GKN Kent alloy wheels, 6JK x 15 in.. which have been optionally available on V12 saloons and coupes for some months.
The all-disc braking system is borrowed from the rest of the XJ family. The ventilated front discs are of 11.8 in. diameter with four piston calipers, while the inboard rear discs are of 10.9 in. diameter. There is a Girling in-line tandem servo and incorporated into the front-to-rear split hydraulic system is a pressure differential warning actuator which shuts off one circuit should there be a failure.
Driving the XJ-S
If the looks have not inspired this Jaguar enthusiast writer into adulation for the XJ-S, a drive back to the Jaguar factory along a varied route from the Cotswolds reminded him that the questionable aesthetics are only skin deep. Beneath the surface of the XJ-S is probably the quietest, smoothest, fastest and best-handling production car in the world: there are some cars which beat it in individual departments, but the writer can think of no other which can boast such a perfect combination of all these attributes.
The pre-production test car was not without its faults, however. For starters there was the uninspiring Borg-Warner automatic gearbox to attract the identical criticism we made about that of the XJ 5.3C: poor kick-down, a low torque converter stall speed and so the imposition of an acceleration lag in the 45 to 50 m.p.h. cruising region, when the engine is ticking over at well below the 3,000 rpm. limit at which it starts to breathe. There is one good thing about the XJ-S which you don’t get with the XJ 5.3C — you can buy it without that Borg-Warner box . . .
Other criticisms — only two spring to mind — front seat cushions needed tilting up slightly to prevent the occupants sliding forwards under braking and the handbrake fouled the arm-rest when applied. These faults ought to have been eradicated from production cars.
This car was so deceptively rapid down the straights, calling for heavy braking into corners, that at first it appeared to be a “point and squirt” machine. A glance at the speedo meter dispelled this — 120 m.p.h. came up so easily that we were braking sharply to 80 m.p.h. or so for a corner which lesser cars with sporting pretensions would be taking at 60 or at most 70. In spite of the added burden of automatic transmission, the test car’s brakes were magnificent in feel and performance, although they did lose a touch of their effciency after a deal of heavy punishment.
Jaguar have always been brilliant at producing a compromise between good handling/roadholding and ride comfort. In the XJ-S they have excelled themselves. There is considerably more feel and feed-back through the now superb power steering, roll is considerably reduced from that of the saloons giving the car a tautness which makes it feel so much more controllable, and there is less understeer. My colleague in the test car found himself entering a sharp right and then left over a bridge at entirely the wrong attitude and speed, having expected a continuous right: in rally driving fashion he flicked out the tail in the wrong direction to scrub off speed and then flicked it back again to line the car up for the left-hander, which it took without drama. We were both amazed: the XJ-S had responded to the quick changes of direction with the alacrity and precision of a rally Escort.
This sort of rapid motoring is accomplished with a minimum of fuss and noise. There is a distant whirring when the engine is pushed in low and intermediate, but at any cruising speed the engine is almost totally silent. The whole car is flooded with sound-deadening material, Jaguar’s great knowledge of engine and suspension insulation is brought into play and combined with the Sayer aerodynamics this machine is almost as noiseless as one can conceivably achieve from a moving object. This feature, the comfortable seats (except under heavy braking) and the efficiency of the Delanair automatic air-conditioning we have praised highly in the past, make the XJ-S into one of the pleasantest — and fastest — four-wheeled passenger environments in the world. This is a stupendously good motor car, a credit to British Leyland, Jaguar and a much-needed fillip for the British motor industry as a whole in the eyes of the world. — C.R.