Road Test - Porsche 911 Tiptronic

Automatically Smart

More than a quarter million Porsche 911s have been made since the September 1963 inauguration of a production car that actually deserves that abused adjective, 'Classic'. More than 35,000 Porsches of all types reside in Britain. Few of those owners would dispute that the 911 in its post 1989 Carrera 2/4 body continued to embody every element of the Porsche tradition for durable speed.

There are faults, the dated and fiddly cabin ergonomics probably the most serious everyday setback, but the 911 remains the standard for lasting value by which every other performance contender in the £40-£50,000 class must be judged. A remark that is more than usually relevant when our recessionary times have forced even Porsche GB at Reading and AFN in West London to reduce employment.

Flat six has lifted the 5-speed manual 911 into the 160mph class with 0-60mph in less than six seconds. Yet the clever Tiptronic manual/automatic 4-speed transmission maintained almost exactly the claimed 159mph, slashed through the annoyance of every day suburban driving and allowed a very respectable 0-60mph two way average of 6.2 seconds.

Consumption of the cheapest 95 octane fuels averaged fractionally under 18mpg for a test that embraced the delights of a full test session versus the Correvit electronic timing gear.

Major changes that coincide with the introduction of the Carrera 2 were made possible by the 1989 debut of the Carrera 4, that all-wheel-drive reincarnation of the markedly rear engine theme (now 61% rests over the rear wheels of a Carrera 2) utilising a more coherent current vision of the traditional 911 outline. For the Carrera 2 it meant the adoption of standard power steering, the latest in ABS electronic antilock brakes and the electrically raised and lowered (at 50 and 6mph) rear spoiler.

Because the 15% of body parts that Porsche list as unchanged (front wings, bonnet and much of the rear engine cover) are above the bumper line, the visual impression is that the 911 is little changed, but the company assure us 85 per cent of those galvanized sheet steel components did have to be changed. The company offers a ten year anti-corrosion warranty and backs this in Britain with three years for paint and two years for all mechanical and electrical components.

Most aerodynamically effective panels are hidden from sight. These are the trio of front end panels that provide a flat under body section in conjunction with the panels that now wall in both engine and exhaust.

Kerb weight has been increased by just over 300Ibs in the 2 + 2 coupe over the 1989 model, reflecting the extra features provided and considerably enhanced body strength.

At extra cost the customer can buy two or 4-WD engineering in a wide choice of revised bodies. These begin at a traditional Targa (from £49,411 to £56,379, according to power train), and power top cabriolet (£53,114 to £60,082). In these recessionary times you might even find a cancelled 911 turbo order, but that 320 bhp package now has a list cost of £72,993 and the company were not expected to receive their own demonstrator much before Spring 1991.

Porsche are continuing to supply swift practicality that owes most to its sensible size and the manufacturing standards of the 1988 Zuffenhausen 911 factory in extending the extraordinary life of the 911 model.

Technical Analysis

Also owed to the Carrera 4 was the redevelopment of the boxer six cylinders. At 69.4 bhp a litre Porsche claimed the highest bhp/litre figure in the World for a normally aspirated, catalytic convertor, two valve per cylinder, production engine. That was at the November 1988 press launch and much of the efficiency is traced to twin sparking plugs for each cylinder.

More significantly the growth from 3.2 to 3.6 litres, a dual ignition system inspired by their commercially unsuccessful foray into aviation with the flat six, and a resonance tuned intake system (complete with flaps to divert intake air path along two diameters of resonance intake manifold tubing), have been developed to yield the widest of enjoyable power bands in production. From 1700 to 6600 rpm more than 70 per cent of maximum torque is at your disposal.

The Tiptronic transmission features the work of an alliance between Porsche at Weissach and the development engineering departments of Bosch and ZF. The chief customer benefits are provided by sensitive microprocessor electronics and the wide use of sensors to guard against distinctly unsporting automatic gearbox gestures, such as shifting up before a bend (it senses the suddenly lifted throttle) or during a corner (it detects insufficient lateral stability reserves). Porsche point to the double clutch `PDK' (Porsche Dopple Kupplung) gearbox of the World Sportscar 962C as the heritage of this gearbox, but the road unit dispenses with twin clutches and is a further conversion of the new Simpson gear 5-speed. The widely spaced four ratios rely on the fast lock up of conventional hardware such as a torque convertor and the diverse action of planetary gear sets under sophisticated electronic management to provide its unearthly speed and fluid change qualities.

The 'Tip' part of the name comes from the German to flip the gear lever around in a sporting manner, and you can be sure there was no temptation to hark back to the Sportomatic brand name of the last Porsche 911 alternative to manual transmission, which ceased production in 1979.

The gearbox offers two shift pattern 'gates', manual selections simply made by pushing the lever forward in the logical + ' plane, or down via a `-' indication. The automatic is conventional in its PRND321 layout, but you can find access to the manual gate from 'D', so the permutations are extensive. The selected ratio is displayed upon the instrumentation, but said illuminated display could be larger and more legible.

Studying the internal ratios shows some wide gaps that are evident to the driver, so it is no surprise to learn that additional forward ratios are number one on the development priority list, along with further internal pump efficiency and torque convertor development.

Whilst the Carrera 2/4 programme brought extensive technical features to the 911 that it had not previously offered (particularly anti-lock braking and power steering), Porsche continue to mildly refine the recipe. For 1991 a conversation with former Porsche racing Champion Steve Kevlin at Porsche GB revealed that coil spring rates have been mildly increased and that the rear end roll bar was down from 21 to 20mm. A more obvious suspension change comes when you specify the 1991 Sport suspension which 'comprises stiffer sport shock absorbers, springs and front anti-roll bar' according to the company.

Other minor 1991 changes cover details like rear seat release and central locking that allows the bonnet/luggage area lid to be lifted without triggering the alarm.

Action

Having studied all the changes that have been made to the 911, it was something of a relief to find the legend in good road and circuit health. Especially as the Tiptronic, for all its electronic sophistry, still amounts to a purist sacrilege; the automatic 911.

In fact the everyday ability of the 911 is enhanced by the presence of Tiptronic. The change quality and speed is the best I have ever experienced in any kind of automatic, its seamless speed only hiccuping if the driver fails to match rpm to road speed on a manual downshift. It would also be advantageous if the first was a little less protected from selection, locked out for all practical purposes outside a virtual stop and pull away situation. Acceleration, away in second gear courtesy of the torque convertor, is far from sporting.

More important than the excellent figures recorded in our data panel, is the sheer accessibility of that performance. Using ten of their own employees as guinea pigs, Porsche checked the 0-62 mph abilities of the manual 5-speed versus the Tiptronic; only three Porsche people could better the 0-62 mph times set in the automated example.

There is also the point that the figures we print are so consistent. We tried two drivers, and the automatic mode versus manual selection, and still could only find fractional time differences. In the Tiptronic model one does not juggle rear end traction versus horrifying rpm and clutch consuming antics; you simply motor off with a modicum of rpm built against the foot brake and torque convertor action.

The times and speed recorded were exactly in line with conservative Porsche predictions and felt the Porsche performed not just impeccably, but with a safety reserve that thoroughly endorses the new body and its substantially revised chassis (wide based aluminium front wishbones, self correcting rear axle, Bridgestone RE71 tyres).

The 911 is far from quiet roaring along at 159 mph over concreted block banking, but conversation was possible without our hearts trying to escape into our mouths, for it tracks notably more securely than did the previous 911 at 151 mph.

Our road impressions confirmed that the 911 is now a much more secure, yet still exciting driving experience. A good example was a greasy winter road full of the second and third gear swerves that could set the previous 911 three severe challenges; braking without a wheel locking; avoiding strong turn-in understeer; attempting to cancel terminal final oversteer.

The Carrera 2 dealt with such challenges comfortably, and the Bridgestones were still only just beginning to allow the complete car to drift gently wide when the Goodyear-shod Sapphire RS Cosworth behind was wandering from lock to lock in search of any cornering grip whatsoever.

Freed from clammy palms and haunting fears that even the best in the business cannot maintain control over some of the earlier examples (particularly original 911 Turbo), we enjoyed our mileage more than ever. This is the highest praise we can afford, for 911s have always provided a brand of motoring not approached by any other marque for balancing leisure excitement and working practicality.

Those who had not tried the 911 format before commented warmly on 'the lack of width, it makes the 911 feel so much more usable', and steering that is 'beautifully weighted. It so fluid and makes smooth, satisfying, progress easy. The only road car I have tried that approached the BMW M3 in this respect felt one charger.

The cabin layout around that informative steering may please 911 conservatives, but the writer feels Porsche could have been braver about a more complete overhaul. The five dials and their seven red needles are fine, but the distinctly scatter-brained 4 switchgear is almost English in its studied eccentricity. Items such as the small fascia rockers for sunroof and rear window wipe are well hidden and the rear screen heater is a pull knob that is a stretch away on the central dash.

The two pedal layout with no formal footrest (but plenty of space) is easier to manipulate than the manual model. We had standard front seat outlines with the benefit of electric height adjustment, but would have also liked fore and aft electrical assistance at that optional cost, or to dispense with that feature completely. The 911 could stand a diet in 1991, and there will be the option of buying a lighter weight Carrera RS version (based on the Carrera racers and 260bhp in 1230kg, or less). You may have to use some ingenuity to secure a place in the RHD queue, supplies limited to 150; the LHD total is only scheduled to reach 1800 examples.

In motion our only quibbles with 911 delights are now not centred upon their traditional roadholding quirks — because the new model had enhanced its abilities to the point where only those who persist in pushing beyond normal road limits will be punished — but on ride.

Owners of the previous model comment frequently on this aspect, and the abbreviated wheelbase 911 remains noisy over many motorway surfaces. It dislikes road joints (such as concrete slabs) with a ferocity that is almost familiar from the writer's even stubbier Honda coupe. I do not think I could recommend the harder yet Sport option until the potential customer had tried the standard layout, which is much more comfortable as soon as you tackle the kind of quicker motoring that a 911 absorbs so pleasurably.

Judged as a 160 mph coupé that provided enormous pleasure, we felt that a commuting 16.7 mpg on the cheapest unleaded and a Leicestershire motorway/ country run at 19.2 mpg were absolutely acceptable. A multiple function on-board computer readout proved accurate to within 1 mpg on cross-checked runs and emphasised that 20 overall mpg was well within motorway reach and that the front tank with traditional nearside wing access will allow 265 miles at our near 18mpg average before the 10-litre reserve is required.

Verdict,

Porsche overhauled the 911 concept for the nineties, and beyond, with conscientious enthusiasm. Their Weissach project engineers genuinely enjoy their work and it shows in the durable excitement that the 911 has created in a 27 year public life.

There are details that (disappointingly) did not receive the attention they deserved, but the overall effect is still of a massive all round improvement. Ultimate enthusiasts should find that the Carrera 2 RS answers any suggestions that the 911 has now been tamed into senility, but to somebody like the writer who has track tested more than 20 examples of the breed as well as performing this kind of full road test at regular intervals since 1975 the Carrera 2 exceeded expectations.

I would highlight the safer, yet still enjoyable handling; sharply enhanced road grip; excellent ABS braking and the enthusiastic breadth of that 3.6-litre engine's pulling power as key attributes for the later model. As to the transmission, I would heartily endorse Tiptronic effectiveness, but would comment that for those without an urban slog the Carrera 2 five-speed is a vast improvement over previous Porsche transaxles and that it now requires no adjustment of driving technique to deploy the manual model effectively.

The 911 deserved to live on. The Carrera 2 reincarnation, especially with Tiptronic transmission, is probably more attuned to the conditions of today than any 911 in that honourable production history. JW

MOTOR SPORT Test Results – Porsche 911 Carrera 2 Tiptronic

Specification

strong>Engine: Air-cooled, light alloy, horizontally opposed six cylinders; SOHC per bank operates two valves per cylinder. Capacity: 3600cc (100 x 76.4mm). Dual ignition system activates two spark plugs per cylinder. Bosch L-Jetronic plus Digital Motor Electronics (DME) fuel injection and ignition management; 11.3:1 Cr. Max Power: 250 bhp (4) 6100 rpm. Peak Torque: 228 lb ft @ 4800 rpm.

Transmission: Electronically commanded Bosch-ZF Tiptronic 4-speed rear transaxle. Rear-wheel drive, Tiptronic utilising torque convertor, planetary and Simpson gear sets. Final drive 3.667:1.

Body: Steel monocoque 2-door coupe with electronically raised and lowered back spoiler. Petrol tank of 77 litres/16.9 gallons. Drag coefficient: 0.32Cd.

Dimensions: Wheelbase, 89.45 inches/2272mm; front track 54.33in/1380mm; rear track 55.09 inches/1374mm; width 65.04 inches/1652mm; length 167.3in/4250mm; height 52.0in/1320mm. Kerb weight: 2970Ib/1350kg.

Front Suspension: MacPherson struts, coil springs; twin tube low pressure gas damping; 20mm anti-roll bar. Steering: Power assisted via servo pump from toothed belt camshaft auxiliary drive; rack and pinion, 18.45:1 ratio, 39.2ft turning circle.

Rear Suspension: Light alloy, semi-trailing arms; concentric coil springs and twin tube telescopic gas dampers; 21mm anti-roll bar (20mm for 1991 models).

Brakes, Wheels, Tyres: Servo-assisted, vented 11.72 inch/298mm diameter front discs; vented rears of 11.73 inches/299mm; Bosch electronic anti-lock braking. Light alloy 6J 16 inch front wheels, 8J x 16 rears. Bridgestone RE71 205/55 ZR 16 (front) and 225/50 ZR 16 rears.

Price: £47,198.39p, UK taxes paid. Priced options on test car were: electric steel sunroof, £1,412; heated seat, adjustable temperature, £226.75; sport seats with electric height adjustment, £553.16; dark green upper front screen tint, £63.64. Total car price with options, £49,454.81p

Manufacturer/Importer: Porsche Cars Great Britain Ltd., Bath Road, Calcot, Reading, Berks RG3 7SE.

Claimed Performance: Max speed, 159 mph; 0-62.5 mph, 6.6s.