It used to be fashionable, whenever anyone mentioned the Porsche 911, to talk at length about the odd place Professor Porsche had chosen to mount his flat-six engine. The idea of slinging your car’s heaviest component outside its wheelbase at the rear, thereby concentrating two-thirds of its mass at the rear – the wrong end for stability – struck many as distinctly ill-advised. Even 911 experts talked of ‘knife-edge’ oversteer and ‘tail-happy’ handling.Elsewhere, the rear-engine layout (vehemently condemned by US safety campaigner Ralph Nader) was the death of quite a few rear-engined cars: the Chevrolet Corvair, the Renault R8 and R10, the Simca 1100, the Skoda Estelle and, eventually, the huge-selling VW Beetle. The on-limit handling of rear-engined cars was unsafe, critics insisted. A rear-end breakaway could never be recovered. The reality was never so dramatic, but it all smacked of the heroic test pilot going into a flat spin for the last time.This campaign nearly killed the 911, too. There was a point in the late ’70s when company bosses at Zuffenhausen accepted that their rear-engined sports car (already diminished and uglified by crash and pollution legislation in the US) was going to have to die. So they quickly conceived the 928 and 924 as replacements, and began talking up a brave new Porsche world filled with front-engined sports cars.Then came the revolution. Buyers insisted that they didn’t want Porsches with front engines. Ford made cars like that. They demanded a continuance of the 911’s unique balance of qualities – compactness, agility, timeless styling and that fantastic engine – and any fool could see these were directly attributable to its unique layout. They kept right on ordering 911s, and those orders saved the car. Porsche started refining away the car’s famous drawbacks with renewed vigour, a process which continues to this day. A great car was saved by its own authenticity.About a decade later, the same desires motivated me when I set out to buy a 911. I’d enjoyed owning a Ferrari for a few years, but had been unable to live with its impracticalities. My ideal was a machine with equal breeding and performance, but more durable and useful – in other words, a Porsche 911. With the help of a car-trader friend, I hawked myself in The Sunday Times as a cash buyer, and finished up with 10 cars to choose from. The best was a 1988, 18,000-mile, 3.2-litre Carrera coupé in gunmetal grey.For two reasons, I’ll never forget the day I took delivery. First, it was the first day of the 1991 Gulf War, and as I wrote the cheque I remember wondering what this would do to Porsche prices (answer: nothing significant). Second, to celebrate my ownership I set off on one of the great drives of my life, a long looping solo strop from home in Gloucestershire to the welcoming roads and fantastic scenery around Crickhowell on the edge of the Brecon Beacons. And 14 years on, it’s where we Autocaristes still take cars when we want to enjoy them. There was certainly no better place to choose when, recently, a new Porsche 911 Carrera S cabrio came my way.So much has changed about the 911 since I owned one. Everything, you could say, but the spirit. This became apparent for the first time as I drove out of London on the M4 and discovered that the motorway speed you can reliably get away with in a 911 – 87mph indicated, 84mph actual – still corresponds precisely to 3400rpm in this 3.8-litre, 350bhp car’s top gear (sixth), just as it did in my old 3.2-litre, 231bhp five-speeder 14 years ago. In fact, looking at the new car’s tacho needle, I could instantly recall my old F-plater’s rev counter graduations, and see precisely the same angle on its needle. It was eerie, and wonderful. But then Porsche has always traded hugely on continuity. You can quibble about weights and dimensional changes and engine capacities and model nomenclature. Hell, there have been four root-and-branch revisions of the 911 since my old car was the thing to own. But the seminal stuff, the things that make the Porsche 911 unique, are exactly the same. These are the things that rise above the rest – the brilliant packaging and the almost unearthly precision of the controls.On packaging, start with the driving position. The 997 cabrio places you perfectly in the car, backside an inch off the floor, equidistant from front and rear contact patches. You’re in unfettered cabin space, supported everywhere between knees and shoulder blades by the most perfectly designed leather bucket seat ever to grace a sports car. Your seat is uncompromised either by an engine bulkhead pressing from behind (mid-engined supercar) or a huge, wide, centre console/engine cover (front-engined GT). The steering wheel, a bent-arm’s distance away, is set high and nearly vertical. Perfect. The pedals exactly meet the balls of your feet. And if you close your eyes and reach with your left hand to the spot that seems natural, it’ll close over the gearlever.You’re closer to the fascia than in most supercars, which helps ergonomics. You’re also not far from the windscreen, which is set more upright than most so you continue to see well in rain and don’t get confused by instrument reflections at night. The 911’s unique mechanical layout also allows the car a shortish wheelbase and a body no wider than a normal car’s (rare in a supercar). This and good visibility mean the 911 feels agile and easy to commit on narrow roads and in town. Yet despite the compactness there’s still enough cabin space for a pair of occasional seats, which owners will tell you are a boon, the difference between owning the car or not. Finally, your 911’s smaller size (coupled with Porsche’s stern efforts to cut engine mass) mean less overall bulk. Zuffenhausen’s honest-to-a-fault technical specs reveal a 1550kg kerbweight for this car, 150-200kg less than rivals.Now for the controls. Nobody ever wrote a poem about a clutch pedal, which is no surprise given that it’s buried out of sight in a dusty footwell. But in this Porsche, it’s a precision instrument. Even with the car static, you can sense from the subtly varying efforts along its stroke exactly where the take-up point is. On the move, it’s strong and accurate, the kingpin in a system which delivers brilliant sequences of perfectly timed gearchanges, whether you’re plying village streets or snapping between ratios at 7200rpm on one of those superb 10-mile sprints still possible in Wales, where you can see the next three apexes coming, one after another. The time needed to dip the clutch harmonises exactly with the fall or rise of revs between ratios, which in turn matches the speed of your hand, smoothly snicking the next ratio.The best expression of this all-round excellence is the third to second downchange, a quick dog-leg movement which often has to be pulled off with accompanying subtle throttle control, when you’re braking, or near obstacles, with some pretty accurate steering to be done at the same time. In the 911, you always seem to hit it perfectly. You can congratulate yourself on your expertise if you want, but it’s really Porsche’s achievement in honing its controls to be the most predictable and the most accurate in the business.No surprise, of course, that the 3.8-litre mill is magnificent. For decades, this flat six and its ancestors have been among the world’s finest engines and this one has only grown in smoothness and response. But if you concentrate on performance figures alone (182mph, 0-60mph in 4.6sec) you’ll miss this Porsche’s point. There’s nothing explosive about its acceleration; that implies a lack of ultimate control, whereas this is one of the most controllable ultra-fast cars you can buy. Even blipping the accelerator is an exercise in precision: after a bit of practice you’ll be adding engine revs to smooth downchanges the way a fiddle player chooses notes for a violin solo.Don’t mention the tail-happy thing. It’s no longer a relevant property in a road-going 911. Wet or dry, this car’s huge tyres, wide tracks and several levels of slide-taming electronics keep nose and tail pretty much in line, no matter what. Powerslides are possible as a curiosity, but only with the hands of a more skilled and committed driver than me on the wheel, and with the Porsche Stability Management well and truly switched off. The steering set-up is as close to perfect as any: it’s beautifully weighted, perfectly geared, accurate and lightly damped against tramlining or kickback.The controversial bit, to my mind, is the car’s frequent lack of ride composure, a result of its rear-heavy layout. Despite clever adaptive damping and several selectable ride levels (including one which practically eliminates suspension altogether) the 911 has a tendency to bob about uncomfortably at the nose on uneven surfaces, especially when a light fuel load stresses its imbalance. You feel the effect in conditions which simply don’t bother mid-engined and front-engined cars, and it’s no wonder, given that the 911 (like nearly every car on the road) is stiffer at the rear than the front. The mass behind the rear axle causes the rear wheels to act as a fulcrum and the nose to bob about over bumps on its relatively softer front suspension.Even with the roof missing, it’s lovely on reasonably smooth stuff, and the effect on rougher roads is not new; it has been implicit in the rear-engined Porsche for over 40 years. But I reckon it’s now more intrusive (well, noticeable) than ever, simply because the car is so good in every other area. Does the buyer care? The enduring demand for the 911 says he does – in spades. Would I care, if I found the money? Not at all. But I’ll be surprised if Porsche’s exacting engineers can tolerate such a fundamental flaw for long. I’d like to know what’s in their minds, even now, to refine it out of sight.