The Jaguar XK150

Road-Test Impressions of a Really Fast, Luxuriously-Appointed Coventry-Built Coupe

The excellence of the Jaguar is now proverbial and it was a pleasure to drive again behind the famous twin o.h.c. six-cylinder engine, which has won so many sports-car races for the Coventry manufacturer, while road-testing the latest XK150 coupe.

There is no question but that the Jaguar provides very real high-speed performance, not only in respect of a maximum speed exceeding 125 m.p.h. but because roadholding, steering and braking are in keeping, Clubroom accounts of creditable journey times being no excuse for exaggeration where the driver of an XK150 is concerned.

For an outlay of under £1,800 the purchaser of this latest addition to the twin-cam Jaguar family buys more safe speed and convenience than it is possible to obtain elsewhere. It can almost be said that the engine makes the car and the smooth flow of power from beneath the Jaguar bonnet is one of William Haynes’ greater achievements. Here is a power unit of 3.5-litres capacity, happy to burn normal pump fuels, which delivers its 210 b.h.p. completely unobtrusively and which runs safely to beyond 5,500 r.p.m. in spite of its size. Indeed, the ” red ” on the XK150 tachometer is between the 5,500/6,000-r.p.m. markings yet this high-speed racing-type power unit is quite docile and will pull away from under 20 m.p.h. in top gear. The car tested had overdrive on the highest ratio, controlled by a flick-switch on the extreme right of the instrument board, and in overdrive, even at 120 m.p.h., engine speed is a mere 4,764 r.p.m., while 5,500 r.p.m. in normal top gear represents almost 110 m.p.h.

The Jaguar power unit, is thus working at all times well within itself. Apart from this application of lazy power there is the continuous surge of acceleration carried high up the speed range. For example, to reach 60 m.p.h. from rest occupies 8.5 seconds and 90 m.p.h. is attained from a standstill in under 20 seconds. The ” century ” is achieved in 25.2 seconds, while speed can be increased from 70 to 90 m.p.h. in a mere 7 seconds, using third gear, or the XK150 may be accelerated from 80 to 100 m.p.h. in just over 10 seconds, in normal top gear. Such performance, allied to maxima in the gears of 18, 46, 69 and 115 m.p.h., with a genuine 125 m.p.h. available in overdrive top, which steps up the normal 4.09-to-1 ratio to 3.18 to 1, given a clear run, puts the Jaguar amongst the very fastest cars in the land.

A speed of over 100 m.p.h. and super-sports acceleration is not pleasurable under prevailing traffic conditions unless matched by adequate road-holding, braking and general controllability. The Jaguar is more than adequate in these respects.

The steering, very heavy for parking, lightens up at speed, although it is never really light steering, considerable castor-action, which spins the wheel through the lingers after a corner, having to be overcome. But this is accurate, if somewhat spongy, steering, asking 21 turns, lock-to-lock, the turning circle being small (33 feet). But it is steering which transmits some kick-back; the four-spoke wheel, with horn-button in the centre, has an instantly-adjustable column, and is set near to the vertical.

The suspension gives a rather dead ride but effectively kills road shock, yet is firm enough not to promote excessive roll when cornering fast. However, there is a sense of vintage-style flexibility about the chassis and although normally not noticeable, over really rough or ripply surfaces the back axle makes its presence felt, reminder that the action of the rear wheels is not independent. This may be because 0.5-elliptic springs are employed at the back, not the 0.25-elliptic springs and ingenious linkage found on the 2.4 and 3.4-litre Jaguar saloons. The hypercritical may perhaps feel that the Jaguar chassis is not so advanced as the splendid power unit.

In general, however, the XK150 handles splendidly, especially in the hands of big-boned, bowler-hatted Britishers. The Dunlop RS4 Road Speed tyres do not protest audibly under rapid cornering, and the car feels safe up to its very high maximum speed. The brakes, in particular, are one of the outstanding features of this outstanding car. They are 12-in. Dunlop disc brakes applied with the aid of a Lockheed vacuum-servo. They really are superb, not only on account of their powerful retardation and complete absence of fade but because they are in no way fierce, stopping the car effectively without the driver having to be sensitive in order not to lock the wheels. There is scarcely any lag in the servo action, although, of course, if the engine stops heavy pedal pressure becomes the modus operandi. These Dunlop brakes are so unobtrusive that they might be mistaken for very good drum brakes—until the user gets back into a drum-braked vehicle, when he immediately awards the Jaguar very full marks! Under light pressure the brakes, however, emitted a horrid squeal. The fly-off hand-brake, on the passenger’s side of the tunnel, is rather heavy to use but absolutly effective.

Adding to the joy of these excellent control factors is a short, rigid remote-control gear-lever mounted at an unusual but very convenient angle on the transmission tunnel. It is the sort of gearchange the driver operates as rapidly as his hand can move, so it is all the more unfortunate that the synchromesh just cannot compete and a nasty jar intrudes.

Indeed, in matters of detail the Jaguar disappoints, because there are items which seem to lack the touch of experienced drivers in the planning of this fast coupe. The seats, for example, are deep and luxuriously upholstered but the driver would appreciate more support from cushion and squab, and on the test car the seat was insecure in its slides. The pedals are biased to the right, so that the driving position is not entirely natural, while so low is the seat that a driver of average height can only just see both front wings.

The steering-wheel rim is conveniently thin but not sweat-proof. Below it on the right extends a stalk for operating the self-cancelling direction flashers; this might be placed slightly higher up the column, a shade nearer the wheel.

The doors tend to bounce open unless slammed and, open, foul high kerbs. Curiously, they lack “keeps.” The luggage boot is roomy if shallow and there is access to it from within the car, although small objects stowed thus soon slide inaccessibly to the back of the boot. The boot lid locks and has a self-propping strut, but it tended not to shut, one corner sticking open. The spare wheel lives below the luggage, under the floor.

Behind the seats, which possess folding squabs, are two (very) occasional seats, useful only for very abbreviated children. Occasionally petrol fumes made the interior of the car objectionable, usually after a spit back from a cold engine. The accelerator action tended to jerky running when opening up from low speeds. The doors have quarter-windows. When fully open, that on the driver’s side tended to remove skin from the knuckles of the right hand as the steering wheel was turned, while dazzle from the sun on the plated beading along the base of the instrument panel occurred under certain conditions—minor criticisms, but ones which bear out our statement that as a connoisseur’s fast car the Jaguar can be disappointing. The main windows require just over four turns, fully up to fully down. Additional ventilation is provided by toggles enabling the back windows to be slightly opened, and two scuttle ventilators, operated by levers in front of the door openings, are also provided. All this ventilation is a good thing, because the gearbox gets quite hot and blows warm air up its gaitered lever.

Each trailing door possesses a rigid pocket of generous capacity, a drawer-type ashtray and has a sliding interior handle. There are also small armrests, formed as door-pulls. Upholstery is in high-grade leather; on the test car this emitted an unpleasant odour, perhaps arising from some cleaning material.

On the XK150 a polished veneer facia has given place to an upholstered panel. On this the tachometer, reading to 6.000 r.p.m. and figure-calibrated in steps of 1,000 r.p.m., with inset clock, and a 140-m.p.h. speedometer figure-calibrated every 20 m.p.h., with total and trip-with-decimal mileage recorders, are mounted centrally, supplemented by ammeter, petrol gauge marked 0.25, 0.5, 0.75, F, and a combined oil gauge and water thermometer. Normal oil pressure is 40 to 60 lb./sq. in. and temperature remains at 65 to 75 deg. C. under hard driving. The speedometer incorporates the headlamps fullbeam warning, and the tachometer the arrows showing which direction-flasher is in operation.

A central facia-sill switch operates the flashers but is a shade inaccessible, the ignition key-hole is separate and the lamps are all controlled from a single central switch marked 0, S, H, F. Push-buttons look after panel and interior lighting, other facia controls comprising two-speed wiper knob, cigar lighter, heater fan button and screen washers. The heater fan and screen wipers work, alas, obtrusively. The doors actuate the interior lights when opened, the passenger is provided with a grab-handle, there is a reversing lamp, and the sidelamps on the front wings have red insets. The boot is also lit. On the facia there is a lockable cubbyhole before the passenger and a smaller, open one for the driver. There is soft crash padding on the edge a the facia.

The rear-view mirror could well provide a better view and it is annoying to have to use the ignition-key to unlock the flap of the fuel filler. The petrol gauge incorporates a low-level warning light. Two swivelling, transparent anti-dazzle vizors are supplied.

Some of the foregoing criticisms may seem harsh and we hasten to remind the reader of the very high’ performance offered by the Jaguar XK150 at what can only be regarded as a very modest price, and of the sheer pleasure to be derived from driving fast this very excellent motor car.

The combination of high speed, very vivid acceleration and safe handling qualities, of which the disc braking is especially praiseworthy, render the Jaguar a superb super sports car, more particularly because the power pours so smoothly from that dependable, docile, quiet and beautifully finished twin-cam engine. The makers request the owner not to exceed 5,000 r.p.m. for any length of time but as this crankshaft speed represents 100 m.p.h. in top gear and nearly 130 m.p.h. in overdrive-top, this cannot be considered a hardship.

The engine picks up speed like a racing-car engine at a touch on the accelerator, yet here the affinity with racing ends, for this is a tractable, quiet power unit, which warms quickly to its work from cold (the twin S.U. type-HD6 carburetters have an automatic enriching unit), and in a test extending over 480 miles consumed no measurable quantity of oil or water. Fuel such as Esso Extra sufficed to suppress all pinking or running-on, while consumption driving hard, was better than 22 m.p.g. Thus, with the 14-gallon tank, the driving range exceeds 300 miles.

When the bonnet is propped open this power unit with its polished camboxes, is delightful to behold. From a more practical standpoint, the twin batteries are found to be housed, inaccessibly, in the front wings.

Altogether the Jaguar XK150 coupe is a very acceptable fast car, carrying on a great tradition with dignity and enhanced high performance. It is priced at £1,763 17s, or at £1,939 7s. in special equipment form, with Blue Top cylinder head, as tested, while the overdrive, as on the test car, increased the price to £2,006 17s. For the export market a special triple-carburetter version with the compression-ratio raised from 8 to 1 to 9 to 1 is available, said to be capable of 136 m.p.h.—W. B.