The 1975 Jaguar XJ5.3C
W.B. is a little off the mark in saying that the XJ.12 coupe was unquestionably the correct British car for coverage in this Anniversary issue. In fact the original intention had been to feature Jaguar’s new sports coupe, code-named XJ27, Which British Leyland had proposed to announce at the end of July. Labour problems and the Ryder upheavals quashed that idea when the release date was retarded to September 10th; though we have driven this exciting car, as always we are respecting the embargo system. We have become used to abortive attempts to road test Jaguars, a traditional problem over MOTOR SPORT’s past two decades, but this time we were not to be out-foxed. Jaguar we had decided upon and Jaguar it was going to be.
The logical alternative to the XJ27 was the XJ12. 5.3-litre fuel-injection coupe, not so pretentiously “sporty” as the XJ27 but nevertheless a luxury carriage of sporting demeanour and very sporting performance. As this model had been announced on April 30th and was on sale already we anticipated little difficulty in obtaining one. True to form, requests to Jaguar met with zero response, so we bared our teeth, scratched our heads — and rang John Coombs, the Guildford-based Jaguar dealer and famous entrant of racing Jaguars in the past. Yes, John Coombs would be only to pleased to help, but to meet our schedule for the front cover photography we would have to content ourselves with a pre-production, carburetter V12 coupe, ex-property of an ex-Jaguar director. With grateful thanks to John, the car duly presented itself alongside the Bentley on the Brooklands banking complete with his famous registration number BUY 1, once carried so proudly on racing Jaguars. Even so, our Jaguar jinx struck once more, as W.B. has mentioned already. Thanks to Mr. Lucas’s alternator and not to the men of Brown’s Lane, the Lucas battery totally discharged itself, with the aforementioned results and finally total immobility.
A brand-new injection coupe which John Coombs had offered to let us use for detail shots later, arrived in Guildford too late from the factory for our inner colour section schedule, which is where another famous motoring sportsman from the past, Mike Couper, particularly of Brooklands and Talbot 105, BGH 23, renown, came to our rescue. W. M. Couper, the St. Albans Jaguar and Rolls-Royce retailers, by chance had a new injection coupe in their showroom and Mike arranged for us to photograph this in the magnificent grounds of the nearby St. Michael’s Manor Hotel.
Just one small problem remained: how could we publish road impressions without driving the car? At this stage Jaguar’s Andrew Whyte resolved that the British Leyland system had to be beaten; MOTOR SPORT’s Anniversary issue must have words in the white spaces around the Jaguar pictures. The Press fleet had been given over entirely to the XJ 3.4 and the XJ27, so no chance there. It looked like the old adage of “the last place to find a motor car is in a motor car factory” was to be proved true again, until Andrew managed to track down a couple of suitable cars to the Engineering Department.
So endeth the saga of how these first published impressions were arrived at. My driving experience was restricted to an afternoon instead of the usual week of normal usage, but as so much of this 140 m.p.h. coupe is familiar already, this was not so unsatisfactory as it might appear. I found it incredible to recall that the first time I had ridden in an XJ Coupe, again with Andrew Whyte, had been in Scotland 19 months before when the model had been announced alongside the Series 2 XJ saloons. That long delay in releasing the cars to the public had been partially the result of inadequate production capacity but largely because of problems with doors and side-windows in this two-door design. The basic shell of the coupe is that of the now discontinued short-wheelbase saloon, that is a wheelbase of 108.8 in. and an overall length of 190.7 in. against 112.8 in. and 194.7 in. for the current long-wheelbase saloons; removing the centre pillar, or B-post, from a saloon and fitting only one door per side, roughly seven inches longer than a saloon front door, is not so simple. Torsional rigidity of the body presented no difficulties, helped by enlarging the rear quarter pillars. The biggest problem has been to seal the electrically-operated frameless door windows and to effectively guide and locate them within the doors. Jaguar’s Director of Engineering Bob Knight told me that their aim was to enable them to be raised and seal perfectly at 130 m.p.h. and this they had achieved.
Merely hanging the doors was another problem. When complete with electric window mechanism and the hefty W-shaped side-intrusion member, each long door weighs 200 lb. which required strengthened door hinges. There is still a fair amount of “whip” against the A-post when the door is opened wide and a deal of effort is needed to pull the doors to, which could be eased if the designer of the arm-rest cum doorpull included a cut-away further rearwards for better leverage.
Originally the Coupe was intended to take the wind out of BMW’s coupe sales and though it has arrived on the scene too late to do that, a body comparison is relevant. The 3-litre BMW Coupe is a chopped down version of the saloon, the Jaguar retains an identical profile to the saloon, with the obvious benefit of decent rear seat headroom. There is greater width, legroom and seat comfort in the rear of the Jaguar, too. The mechanism for the electric rear windows has meant that the side panels have encroached on seat width, but if anything this has improved comfort; with the centre arm-rest folded down each passenger is locked in a superbly comfortable bucket. With the arm-rest folded up, there remains room for a child between two adults. Rear legroom is identical to that of the old short-wheelbase saloon, which means only just adequate with the front seats at their rearmost and modestly generous with them forwards.
All the trouble to evolve the frameless door Windows is proved well worth while aesthetically when the entire side aperture is opened wide. The rear windows perform remarkable gymnastics to disappear into the side panels. There is fresh-air in abundance and a pleasant feeling of freedom. Switches for all four windows are mounted on the centre console in front of the driver and the rear passengers have separate switches for their windows mounted on the back of the console. The omission of the saloon’s fixed quarterlight bar in the side window changes the perspective and slightly improves vision, but the window guide piece at the leading edge of the door spoils the effect.
The rest of the beautifully-appointed interior is identical to that of the Series 2 saloons; veneered fascia, quality carpeting, sumptuous Connolly leather (though cloth upholstery is optional), cloth-lined roof, a picnic tray and fold-away vanity mirror in the lockable glovebox lid, a lidded stowage compartment in the wide centre-console arm-rest and a splendidly clear arrangement of Smiths instruments (illuminated by fibre optics) and warning lights, including an oil-pressure gauge which should read a healthy 72 p.s.i. in the case of the V12, The important auxiliary controls are steering column mounted, though the main light switch is handily placed on the fascia and the centre console includes the change-over switch for the twin 10-gallon fuel tanks. A centre locking switch is included for both doors but not for the boot. I still despise that twist and turn handbrake under the fascia and wish that Jaguar would adopt a leather-rimmed steering wheel, on the V12s if not the 6s. In terms of comfort I have always found the XJs beyond criticism, utterly exceptional, and the Coupe confirmed this once again.
Automatic air-conditioning is an option on this Coupe. Suffice to reiterate what I wrote on first acquaintance with this new Delanair system, that it is one of the best available. In other respects this Coupe is splendidly equipped as standard, including as it does tinted glass, head restraints, a pushbutton Radiomobile radio with electric aerial and a vinyl roof. Alloy road wheels are optional on the V12 Coupes and Saloons and a chrome side moulding identifies the V12 versions.
Since W.B. tested the Series 1XJ12 in mid-1973, that all-aluminium, 5.3-litre, 60 deg. V12, unique in a mass-produced car, has undergone several changes, firstly for the worse when emission regulations forced the adoption of softer camshafts (one to each bank, of course) and lowered compression ratio, and now for the better in the Coupe with the adoption of Lucas-Bosch D-Jetronic electronic fuel injection. For the time being, the V12 saloons will retain four Zenith carburetters, adopting injection later in the year. Emission regulations are the real reason for this change — this is now one of the cleanest engines — but there are other benefits, too.
Most instantly noticeable is the complete transformation of hot and cold starting behaviour, the bugbear of the carburetter engine. The injection auxiliary “brains”, namely air and water temperature sensors, manifold temperature sensors, throttle switch and trigger signals, report back to the slim Electronic Control Unit in the boot, the main brain which automatically controls fuel quantity and mixture. Hot or cold the engine starts instantly on the key and is controlled immediately to the same constant tickover, whatever the temperature, a great advantage with the standard automatic gearbox. That long churning of starter motor and fiddling with manual choke common to the carburetter version is a thing of the past.
Either 5,343 c.c. V12 engine has so much power in reserve that it would take a back-to-back, straight line test to tell the difference in outright performance. The same things applies to the Saloon v. Coupe comparison, for the Coupe has a mere 49 lb. advantage and identical aerodynamics. Jaguar quote the same 0-50 m.p.h. time of 6.0 seconds, 0-60 m.p.h. of 7.5 seconds and 0-70 m.p.h. time of 9.8 seconds for both engines (the carburetter figures taken with an early engine), though the injected car wins out by just 0.1 sec. over the quarter-mile, in 15.6 seconds. Top speed, too, is quoted as 140 m.p.h. (approx) in both cases. The interesting thing is that a higher final drive ratio (3.07:1 instead of 3.31:1) has been adopted for the injected car, so the figures highlight the power improvement. It has gone up from 254 b.h.p. DIN at 6,000 r.p.m. to 285 b.h.p. at 5,750 r.p.m. Peak torque is less at 294 lb. ft. at 3,500 r.p.m. instead of 301 lb. ft. at 3,500 r.p.m., but the torque curve is much flatter for the injection engine.
On the road, high-speed performance of this injected car is quite incredible, largely because of the uncanny quietness, smoothness and effortlessness of the V12. The speedometer needs watching constantly and while 70 m.p.h. is reasonably easy to adhere to, this XJ demands concentration to tether it to the 50 and 60 limits. The carburetter engine itself was so smooth that it is impossible to say whether injection has made it smoother, but certainly throttle response has improved. One hundred miles per hour cruising is achieved in almost total silence and though I couldn’t try for an absolute maximum speed, at 130 m.p.h. the pressure in the back which had built up from 4,000 r.p.m. was undiminished and that supreme smoothness and silence practically unruffled.
It is almost a tragedy that the Borg-Warner Model 12 automatic gearbox does not match that beautiful engine. It is hampered by a torque converter stall speed of only 2,000 r.p.m., part throttle kick down so low down the speed scale that it is of little use and full-throttle kick down with an overlong delay. It kills performance from low revs, a felony compounded by the injected V12’s inheritance from the carburetter engine of lack of steam below 3,000 r.p.m, though a good automatic would compensate for this. It can lead you into the situation where you pull out from cruising behind a lorry at 45 m.p.h., expect instant response for a rapid overtaking manoeuvre – and suddenly you find yourself sitting there with very little happening. The manual hold gives little improvement and the gear-selector, which requires the lever to be pulled over to the right to allow movement, doesn’t match the refinement of the rest of the car.
Jaguar have seen no reason to modify the all-independent suspension at all for the Coupe; semi-trailing wishbones, coil springs, telescopic shock absorbers, an anti-roll bar and effective anti-dive geometry at the front; transverse wishbones, trailing links and twin coil spring damper units at the rear. Even after seven years of production, the XJ’s roadholding and braking remains superb, but the so-smooth ride dictates a softness which you won’t find in a BMW Coupe. Fast driving provokes a great deal of roll, and though this doesn’t disturb the roadholding it can disturb the occupants. More roll stiffness, particularly at the rear, would give this Coupe the more sporting edge over the saloon as befits its appearance. As it is, it behaves exactly like either wheelbase saloon.
This Coventry company is prone to keep quiet about engineering improvements made during a production run. They have certainly done themselves an injustice by hiding improvements to the power steering, which it totally different to the wishy-washy, overlight system of early XJs. Modifications to the valve in the Ad-West system, common to all XJ models, have made it much smoother, more sensitive and progressive, while the smaller steering wheel adopted for the Series 2 helps also. Now the adoption on the latest V12-engined cars of an eight-tooth in place of seven-tooth pinion in the rack has produced slightly higher gearing. Though still light, it is much more positive, gives far better feel and is a great help to fast driving, making this a very manoeuvrable, easily placed big car.
An afternoon of driving didn’t allow me to check Jaguar’s claims that consumption has been improved significantly by the injection, but the higher axle ratio alone should ensure more economical cruising. Fourteen to 16 m.p.g. is said to he a norm, rather better than 12 to 15 with carburetters. What is more, this should not deteriorate, for the injection system is tamper-proof and indeed should require no servicing; a tickover control screw on the boot-mounted control unit is all that can be changed.
If this new “two-door pillarless saloon” is identical to the four-door saloons in performance and general behaviour, it does offer a certain dash and youthfulness of style which sets it apart, as ought to be the case for £7,280. In performance, comfort and quietness it has few, if any, peers anywhere in the World, a very different proposition to the crudity of the 3-litre Bentley. But just as the Bentley reflected the best that the British motor industry offered in 1925, so does Jaguar’s V12 Coupe today. – C.R.