Road Test: Porsche 928S4

Grandest tourer

When it appeared out of the blue ten years ago, Porsche’s exotic 928 shocked many people. Firstly, it dared to proclaim itself the successor to the revered 911 — but it had a front engine, and water-cooled at that. And then it sported that bulbous bumperless one-piece styling with window openings seemingly punched out of it. In the intervening decade, we have learned that the flat-six will continue alongside the V8, and we have seen the influence of this design watershed spread in diluted form to a wider range of cars. At the same time, the range of cars from Stuttgart has advanced on many fronts, with each of the types having its moment of glory. Lately it has been the four-cylinder cars in the limelight; now, with a completely revised four-valve per cylinder design, it is the turn of the V8.

Most important to the Porsche marketing effort is the fact that the proper order of things has been restored. With one of the most enviable development programmes of any sportscar maker, the Stuttgart cars constantly edge forwards like over-eager drivers sitting on the grid waiting for the green light. Pole position is meant to stay with the 928S, which Porsche calls its flagship, but it has been eclipsed on price not only by the almost mythical 959, but also by the rather ugly 911 Turbo SE.

But if there is one thing more confusing than a flagship which is not the dearest in the range, it must be a flagship which is not the fastest in the range. Being out-sprinted by the 911 Turbo was acceptable; losing out to a four-cylinder of half the size was not. This is exactly what happened when the 944 Turbo roared into the picture with performance in the upper reaches which equalled or surpassed the V8; however, the fifth-generation 928 has been given back the edge over its precocious junior. This is not the first four-valve-per-cylinder version of the alloy V8 to be offered to the wealthy businessman: American customers have been driving a 5-litre 32-valve 928 known as the S3 since 1985, although this “smog special” was rated at 288 bhp, some 30 horsepower less than the current S4, whose vast but wholly controllable 320 bhp output applies to all markets, with or without catalytic exhaust converter.

Feeding fuel to the eight hefty cylinders of the 928 is a Bosch LH-Jetronic system with over-run fuel cut-off, linked to the EZK solid-state digital ignition computer; supremely accurate fuel-flow and individual timing adjustments for each cylinder, controlled by separate knock sensors, allow a high compression ratio of 10:1 in the TOP (Thermodynamically Optimised Porsche) head. In fact this ratio is slightly less than before, but accompanies all-round improvements: not only does the revised design produce considerably more torque, now to a mountainous 317 lb ft, it also burns lower octane fuel, and suffers no loss of power whatever when fitted with the catalytic convertor required by Germany and the USA. A central spark-plug makes for even ignition within the silicon-coated cylinder, while there is no evidence of the low-rev flaccidity which afflicts small-capacity four-valve engines: peak torque is churned out at a textbook 3000 rpm, with the crest of the power curve at 6000. This means significant gains in mid-range overtaking performance over the S2 whose lesser torque peaked at 4100 rpm.

Hydraulic dampers locate the broad and massive power-plant within the narrow-lidded engine-bay. Induction is accomplished in the classic V8 manner, through the centre of the vee, with softly-polished inlet tracts adding only a couple of inches to the unit’s height. Belt tension for the two camshafts per bank is monitored electronically, and the distributor is mounted on the end of one camshaft. A variety of ducts is carefully blended within the curves of the revised nose, which also incorporates a discreet spoiler: the huge ventilated brake discs are rammed full of cool air by one set, while the flow to the combined oil and water radiator is automatically controlled according to thermal load, thus minimising drag whenever possible.

Undeniably a bulky car, the 928 has never been particularly sleek, a fact which one family car manufacturer’s advertising exploited in boasting that its own product had “a lower Cd than a Porsche”. But now that embarrassing 0.39 figure has dropped to 0.34, a real achievement which is due to the softer and longer nose and tail (making the S4 3in longer than the S2), subtly widened sills, a narrow but free-standing tail spoiler, and a large undertray.

Like all current cars from the company, the gearbox is at the back, though in the front-engined models it is attached to the engine by a substantial torque-tube through which the prop-shaft runs. This solid connection reduces any drive-line movement, and provides a firm mounting for the gear shift, should you specify the no-cost option of a five-speed manual ‘box. Standard issue, though, is the four-speed auto, and with the pulling power of an ocean-going tug surging through it, I found myself for the first time quite content to let the machine choose its own ratios.

In many cases the torque-converter of an auto dulls the response of the engine it is attached to; not so the 928. Push the smooth throttle pedal and acceleration is immediate, building up forcibly as the revs rise and accompanied by a brief five-litre snarl. Press harder and the Mercedes-Benz four-speeder snaps down one ratio, shoving the occupants deep into the seats while the tach needle lingers at maximum torque and the speedometer spins in moments towards licence threatening levels. The response is instant and predictable: the driver can feather the throttle to surge ahead in the same ratio, or instantly twitch the box into a lower gear at any point he likes. Determined foot pressure will call up a second downshift with even more dramatic results, but even here the nose lifts only a whisker during take-off.

No need to anticipate overtaking moves by using the selector lever to change down, as I usually do in lesser autos — the Porsche can do the job as quickly and with no effort, at the expense of a thump as it changes from second to third at full stretch. On dry roads, the new larger 245/45 VR 16 Dunlops at the back (the front retains the previous 225/505) are easily capable of coping with the car’s power, not a chirp being heard during gearshifts, and they remain impressive over wet roads, more so probably than the benchmark Pirelli P7. But maximum throttle needs respect in the rain.

It seems a pity that much of the engineering splendour of this vehicle is concealed beneath the flawless paint, for every component has been shaped from the best material for the job and hang the expense — or at least pass it on to the customer, because there are seemingly plenty who will not bat an eyelid as the bill passes the £50,000 mark. The writer of that cheque will probably never see the elegant light alloy castings which comprise the suspension, or the compact four-piston brake calipers which bring race-track stopping power to the motorway, but he will feel the evidence of such care every time he puts the key in the ignition. There is a satisfaction which derives not from bhp figures or acceleration times but from putting a craftsman’s best work to its intended use.

Those alloy front wishbones are mounted in a conventional double set-up, with combined spring/damper, to hold the front wheels in place, but the plump rump of this Grand Tourer is the home of the trend-setting “Weissach axle” which has inspired a new branch of chassis technology — positive rear wheel movement. Many manufacturers have now followed Porsche’s engineers in paving the inevitable angle changes to good use, and indeed the 928 design seems rather simple in comparison with that of the Mazda RX-7 tested last month. It responds only to fore-and-aft inputs, but the effect is similar-it tends to introduce toe-in on the loaded out, rear wheel, minimising the likelihood of oversteer if the throttle is snapped shut halfway throug a roundabout.

However, like any car the 928 responds best to smooth driving, and it clings through the tightest bends in a supremely predictable way. A modicum of understeer tells the driver how hard he is pressing on, and if it starts to increase, a gentle lift of the throttle edges the fat coupe back into line. Its width is not difficult to cope with in itself, given the direct steering, but be prepared to give way in country lanes.

Steering action is good, though perhaps falling short of the super-sharp feel of the same company’s 944 Turbo; assistance varies with both speed and load, giving roughly the same pleasant weight to the leather-bound wheel whether parking or travelling at 120mph. At such speeds directional stability is very good, with little reaction to side-wind, although vertical deflections do set up squirming sensation which feels more to do with the suspension than the tyres. This is most pronounced when cresting a brow, when the car seems to wiggle its hips before resuming its course. And I was surprised to find that it bottomed out at the end of some (admittedly severe) dips.

Overall it deals well with bumpy roads particularly at higher speeds when the rather sharp ride smooths out, but like other Porsches the wheels crash and thump over holes and even cats-eyes, sounding uncomfortable rather than feeling uncomfortable. Tyre rumble is about the loudest single noise over the engine, sadly perhaps, is completely insulated from the driver’s ear except on fulI throttle. Another exception to this vow of silence is when the letter-box of a sunroof is open, which introduces a roar like an express train.

ABS is part of the package, but I did not manage to invoke it, being sufficiently impressed by the normal action of the large ventilated discs and the four pads which grip each one. Dunlop, too, deserves credit for such rapid and consistent stopping.

Opening the heavy door and tipping the seat forward exposes the two rather dainty perches in the back, separated by the massive hump of the transwde. These are small even for older children, and adults are unlikely to be squeezed in at all. Folding the backs down extends the luggage space quite usefully, though, giving a flat surface almost to the front seats. Surprisingly, cargo is better catered for in this supreme sports coupe than in most estate cars— not in terms of volume, of course, but in appointments: a tough luggage net covers the boot floor, there are strap anchorage points, and a quickly detachable cloth cover screens the boot alone or extends individually over the folded rear seats.

Supporting the crew is a pair of rather curvaceous seats which grip the hips much better than they look as if they should, with electric adjustment by some rather muddling switches down the side, and three memory positions. Yet despite all these variations, including lumbar adjustment, which I fiddled with constantly, I could not sit comfortably for more than half an hour at a time.

Other aspects of the driving position are good: the bulky instrument housing moves up and down with the wheel, retaining a good view of the clear orange-needled dials and keeping the switches in fingertip reach. The ignition switch is also in this housing, instead of concealed at some awkward angle down on the column, while the climate is influenced by small sliders on a central panel. There are stalks for flashers (left) and wipers (right), plus another for the Tempostat cruise control for the lazy. The handbrake lever is of the fall-away type and well sited to the driver’s right, together with a headlamp adjuster and the rear hatch release.

Extra vents are let into the door panels, and the driver also has the seat memories and the mirror controls by his right arm. Window and roof controls, though, are easily confused with the rear wash/wipe rocker, all of these being behind the T-bar gear selector.

Wide-angle driving lamps in the bumper allow for instant flashing, and augment the already superb headlamps, while further safety features include heated washer nozzles, and a secondary windscreen wash system which blasts the glass with concentrated cleaner strong enough to remove the usual messy peppering of massacred insects.

Well-equipped, but still inviting you to spend money on options, the 928S4 is far from being the stereotypical luxury car: a Jaguar XJ-S for half the price would be that. Instead it argues forcibly to be a real sportscar, despite its great bulk and its mostly automatic sales. Even at high cornering speeds the 928S4 feels absolutely settled, asking for more acceleration to squirt from the exit of the bend, which can be fed in with complete confidence in the traction available. Pinpoint accuracy is there to be exploited through the wheel, and the massive-looking vehicle flicks one way or the other with almost ludicruous ease.

Combine these qualities with the beautiful finish of components and trim, the busy quiet it exudes on the motorway, and the uncomplaining way it will trickle through M1 roadworks jams, and it is difficult to draw a distinction between the Grand Tourer and sportscar labels. It is a fine compromise in function with no compromise in execution — a hatchback with luggage space which will quarter Europe in a day and provide immence satisfaction while running rings around many another sports aspirant. And if you are likely to be one of the 300 or so who will buy one in a year, who cares what sort of car it calls itself? GC