Jaguar XJ-S V12 convertable

The British ambassador

It is extraordinary how little the shape of the Jaguar XJ-S has altered over its many years of production. True, it has twice lost its head, to become first the Cabriolet and now the Convertible; it has received new bumpers and wheels; the venerable V12 engine has been fairly radically revised to its current May-headed HE specification, and a brand new six-cylinder engine has been squeezed under the bonnet where there was no thought of such a thing at the design stage.

Beyond the factory gates, several specialist outfits have modified the basic Coupe for more performance or more capacity: stiffer suspension, crisper steering, wider tyres and smooth bumper/airdams are all offered with full Jaguar sanction through JaguarSport, co-owned by Browns Lane and Tom Walkinshaw Racing, while further afield one can order a 6.4-litre conversion to the huge V12, manual replacements for the standard autobox, four-seater conversions for the two-seater drop-heads, or the truly beautiful Lynx Eventer XJ-S estate.

In the past one company offered a lengthened full four-seater with raised roof and only recently a quad-cam conversion been developed by a specialist firm which boasts no less than five valves per cylinder, a total of 60, eclipsing in complexity even the 48 valves of the experimental engine which TWR raced in an XJR-9 at Brands Hatch last year.

Yet the essential character of the XJ-S has not been altered by these attentions. The unique lozenge-shaped headlamps are still set into chromed surrounds, and more bright metal adorns both inside and outside. A hidden spoiler buried under the nose is an invisible concession to the laws of physics, and an observant eye will see that the Convertible has a new smooth bonded-in windscreen and no quarter-lights, but it looks very much as it did when the model was first revealed.

Indeed, a recent court-case revealed some XJ-S faking: early cars being refitted with recent bumpers and trim and resold as much newer vehicles.

Under the elegant sweep of bonnet it seems scarcely possible that a fat V12 should fit, but it is all squeezed in with a handsbreadth to spare, the single-cam two-valve-per-cylinder May heads almost invisible under neat straight piping and wiring for the Lucas electronic fuel injection. Their exceptionally high compression ratio of 12.5:1 keeps the 5345cc all-alloy unit on the affordable side of 15 mpg, at times reaching as much as 19 mpg.

Only the long-serving GM Hydramatic three-speed automatic transmission is available in the Convertible; a manual box is offered with the 3.6-litre AJ6 straight-six engine which is part of the coupe range, but therein only one specification and one price for the Convertible: V12, automatic, all leather, all electric, all inclusive, at £38,500. It is the most expensive Jaguar you can buy, but the projection for 1989 is that 5000 of the 12,000 XJ-S cars built will be Convertibles.

Some 80% will go abroad, largely to the United States, where it will champion Great Britain against the home-grown Corvette, Porsche (911 and the new 944 cabrios) and Mercedes, whose SL convertible is the most status-laden symbol of all, selling 12,000 in the USA in 1987. With an all-new SL sports-car just being launched to replace the long-running current model, the XJ-S runs a risk of suddenly looking dated by comparison, but Jaguar will play on its pedigree and racing connections past and present to emphasise the traditional appeal of its luxurious two-seater.

Jaguar’s formerly safe position of being the only mass-producer of V12 engines has now been devalued by BMW, whose 12-cylinder engine only appears in a large luxury saloon, and imminently by Mercedes, which will launch its own version in the new SL. Thus the two German companies are a challenge to both aspects of Jaguar’s range, saloon and coupe. Yet despite the generation gap, the 5.3-litre British Vee in its latest form is still widely considered a fair rival to the BMW, and Jaguar management seems confident about the vital US market for both saloon and XJ-S over the next two years until the new sportscar, commonly known as the F-type, appears.

But if the engine is still up to the competition, the box itself now has an old-fashioned feel. Floods of silent torque, peaking at 317 lb ft, from the huge engine mean that three ratios are enough to get the torque convertor churning at maximum efficiency when the driver sinks the throttle pedal; 3000 rpm marks the crest of the curve, and the box does not allow the tachometer needle to go far beyond this even on the way to breaking 60 mph in eight seconds.

However, this leaves a noticeable gap between top and second which the box is reluctant to bridge. High gearing sometimes finds the engine unprepared for immediate action, and the kickdown is slow to react. With torque like this, of course, top gear acceleration is impressive enough, but it is frustrating to know that there is more to come. If you want instant access to the power, to sweep past a lorry on a winding road for example, the positive answer is to knock the T-bar shift lever back into “2”, open the throttle and shift back to “3”, thus letting the box change up as soon as the pedal is relaxed again, but the down-shift can be very abrupt. All this is unnecessary with the new generation of four-speed autos, with their automatic lock-up devices in top gear and choice of “sport” and “economy” modes. Such a system is now available on XJ6 and the six-cylinder XJ-S, but will not be fitted to the new XJ12.

Power-assisted steering is fitted, and the Salisbury rear axle encloses a mechanical limited-slip differential. All XJ-S models now include the Trues anti-lock braking system, with a high-pressure hydraulic pump as the power source, and a yaw sensor to keep the car straight when two wheels are on the marbles.

A squeeze of the heavy metal door-handle pops open the long door, with its inlaid burr walnut panels and leather armrests; inside, leather, walnut and chrome are almost the only materials to be seen, unless the option of herringbone tweed seat-facings is selected.

Not only is all this beautifully executed, with perfect stitching everywhere down to the fine, soft black hide enfolding the slender wheel, but the traditionally-styled controls do not seem to lose much to more modern ergonomic designs. Long chromed levers make it easy to adjust the twin electric door-mirrors, and large rectangular push-buttons control the major functions.

Air-conditioning is standard equipment and the very effective temperature control is altered by large rotary knobs. If, however, you leave the system on “auto” with the roof open , it will churn out hot air in a vain attempt to heat the entire south of England.

XJ-S managed to avoid Jaguar’s brief flirtation with advanced and illegible instrument read-outs in the XJ40, still retaining four vertical minor gauges between the speedometer and rev-counter, though a row of warning lights above is covered up by the rim of the wheel. Fore-and-aft movement of the wheel is provided for, but I found it set rather high, compounded by the short and flat seat-base which lacks support under the knees. In other respects the latest seats are an advance over the older saloon-type armchairs, with a tighter grip on the nether regions. Adjustments are mainly manual, except for electrically variable lumbar support. Seat heating is built in.

This combination of seat and wheel makes one want to sit upright in the Convertible, but at high speeds with the top down it is more comfortable to duck down a bit to avoid any turbulence. Passengers are pretty well insulated from buffeting once the electric windows have slid smoothly up, but not quite well enough to threaten TVR’s position as builder of the rag-top with the best-sheltered cockpit.

Power operation for the hood was considered essential, partly because of the car’s image and partly because half of the US owners are expected to be women, and is achieved by two hydraulic rams driven by an electric motor and pump. Once two latches are released from the screen rail, a rocker switch on the centre console folds the whole affair, including the rear side windows, in about fifteen seconds; erecting it takes a little longer, but either can even be done while waiting at the traffic lights as long as the selector is in “P” and the handbrake is on. The cast release levers are integral with the hood mechanism, so that the screen rail is left smooth and clean when the top is lowered.

Once up, the padded and lined roof with its heated glass rear window makes an almost convincing coupe, with a smooth, elegant shape which offers remarkable quiet inside, allied with fine views in virtually every direction. A little vision is lost in the blind three-quarters spot, but the ability to properly demist the rear window is compensation enough.

Even the folded package is neat, collapsing well to the rear and below eye-line in the mirror. It is not flush, but a separate tailored cover snaps in place to make it look tidy if one is fussy. Luggage and effects can be stored on the railed platform behind the seats even with the top folded, and there are two built-in lockers which mean that the car may realistically be parked with the top down and still offer a measure of security.

Despite the incorporation of the hood mechanism, this very long car retains a full-sized boot. Even with a fat spare tyre in a beautifully tailored cover propped vertically against the back wall, a large battery box alongside that, and a fitted fire extinguisher, tool case and first-aid kit tucked into the side compartments, there remains a vast square sided hold which would swallow a small cabin trunk. Blithe comments about “chopping the top off” are an unfair reflection on the huge number of modifications which went into the new car. It incorporates 108 entirely new panels, and a further 48 have been altered. Steel tubes have been inserted in the screen pillars and the sills, while front and rear bulkheads, the transmission tunnel and the rear floor have all been strengthened. Even the doors are changed to accept the frameless windows. Extensive computer modelling and prototype testing established the optimum combination of absorbent mountings to maintain as far as possible the Jaguar’s silky smoothness of ride, even though no convertible can ever bean rigid as a car with a roof.

Inevitably the weight has increased, not only with the extra metal but also with the pump, motor, and two rear window winders, rising by 220 lb to 4188 lb, which adds about 0.3 seconds to the 7.6 which it takes the Coupe to hit 60 mph. Similarly the drag factor is higher, though only by one point to 0.39, knocking a barely measurable 1 mph off the Coupe’s 151 mph top speed.

There was a strict timetable attached to this project of only three years, not long in traditional automotive terms. But like most other manufacturers, Jaguar has been addressing the task of reducing these response periods, and elected to try a new approach in this case. This was the “Project Team” principle, in which 12 representatives of all aspects of a new car launch forms team which is solely responsible for the progress of the project, instead of central management guiding this amongst many other tasks.

Another significant decision was choosing to go outside the company for specialist skills, to Karmann, the German concern which does similar work for many European firms. Karmann’s involvement covered the design of the hood itself, the assembly jigs, plus the tooling for the new panels. It also built the fully-engineered prototypes which are the stage before pre-production cars. These were assembled in a new installation at Browns Lane, costing £2 million to build, which will be used for all future pre-production models.

The target of revealing the car at the 1988 Geneva Show was achieved comfortably, and as a result of this success the Project Team concept will be used for more Jaguar projects.

Although a stiffer suspension package is now available for XJ-S Coupes, it is not to be made available on Convertibles since it would exaggerate the modicum of chassis flexure which occasionally makes itself felt. This never lasts long enough to unsettle the car; it shows itself only as a passing shudder over the likes of a badly-installed drain. Under most circumstances the car is treacly-smooth, floating over the awful realities of England’s road surfaces as if they were not there, its six dampers (four at the rear in the independent wishbone unit carried on from the E-type) forcibly calming the motion of the 215/70 VR15 Dunlops. The whole chassis is optimised for effortless and undemanding comfort, but is less effective when rapid switches of direction are called for, when the body begins to roll and pitch.

This is noticeable because the driver is pampered by a high level of steering assistance; small, light movements of the wheel translate immediately into sharp action from the chassis. It feels delightful when parking, but for preference it should tail off more quickly as speed rises. Anti-dive geometry in the layout of the front double wishbones prevents the nose of this long vehicle from dropping when the calipers are gripping the big brake discs, and they do an excellent job on continued high-speed use, notwithstanding the restricted cooling to the inboard rears. The front units are ventilated. Acceleration, on the other hand, brings the nose up mildly, an effect which is exaggerated by the length of the flat-topped wings.

Driven easily, the car understeers more than one expects at the low to medium speeds which most buyers will stick to, tightening its behaviour with increasing throttle until front and rear are sharing the load equally. Impressive at speed, then, but lacking in front-end bite when tackling everyday junctions and roundabouts.

The shift quality of the Hydramatic box is robust, and it pays to feather the throttle at the change point to achieve a seamless transition. The sensation of letting the car go on an open expanse of private tarmac, surging through the first two ratios and on into top with no snarling exhaust or rasping carburettor noises, just the bellowing rush of wind as the speed tops three figures, is a strange one, but memorable for the blending of such performance with such refinement.

Wheel movements are so well damped that it is hard to hear the big tyres slapping in and out of holes even when running with the top down; equally, the muted sound of 12 thrumming cylinders is lost to the sky. Only a brief shiver through the frame and a deeper note from the exhaust betrays the fact that the engine is flexing its muscles. Assembly quality of the whole vehicle, inside and out, is very high, although the rear quarter-lights on the test car occasionally stayed open when the roof had clicked shut.

Having been side-tracked with the Cabriolet, the company is doubly fortunate to have such a fine car to boast today. XJ-S sales, already stronger than ever, are being given a real boost by this long-overdue model, while there is no doubt at all that the Convertible is much the better for being an Eighties instead of a Seventies car. GC

Model: XJ-S Convertible.
Maker: Jaguar Cars Ltd. Coventry. Type: two-seater luxury sports convertible.
Engine: 5345cc (90x70mm) 60deg. V12. alloy block and head, sohc per bank, two valves per cyl, 12.5:1 cr. Lucas electronic fuel injection/engine management. Max. power: 291 bhp at 5500 rpm. Max torque: 317 lb ft at 3000 rpm.
Transmission: RWD. three-speed automatic, LSD.
Suspension: front, double wishbone, coil springs, telescopic dampers, antiroll bar. Rear, independent, lower transverse wishbone with driveshaft as upper link, radius arms, twin coil springs, telescopic dampers.
Steering: rack and pinion, power-assisted.
Brakes: vacuum servo. all disc, ventilated at front, electronic anti-lock.
Wheels and tyres: 215/70 VR15 tyres on 6.5x15in alloy rims. (235/60 VR15 tyres on sports wheels optional.)
Performance: 0-60mph: 7.9 sec. Max speed: 150 mph.
Economy: 17.5 mpg overall.
Price: £38.500.