Driven: 1973 Porsche 911 2.7 RS vs 1992 Porsche 911 Turbo S

It's been a busy half-hour of nervous exploration and negotiation with the little blue monster. But I'm beginning to feel it isn't really set on toasting me and having me as a snack. And so at times – glorious times – I'm goading it on. The reward is a potently visceral mix of sensations, the exact like of which you just don't get anywhere else.

Hang on. Now the relationship is changing again. The sky has rapidly gone black and it's sheeting in rain. The roads round here are all adverse cambers, tramlines, deep puddles and patches of mud. Extreme caution advised.

Photography: Michael Bailie

Welcome to the 1992 Porsche 911 Turbo S. An ultra-light old 911 with a flat-six exhibiting all the boost characteristics of Vesuvius. Dormant for long and unpredictable periods, but liable to leave a deep impression on eruption. Traction control? Not here. This is 1992.

I never want to have a road accident. But I particularly don't want to have a road accident in a very rare car that goes up for auction in a few days, and which is insured for a significant sum.

Mind you, the car I was driving earlier today is valued even higher. We brought them together, the yellow RS and blue Turbo S, because they're two air-cooled-era high points of two sorts of factory 911 tuning. Both are legends. But their characters are poles apart.

RS you'll know about. Renn Sport. Few initials in planet automobile command more reverence. They're the letters that Porsche's Motorsport department lovingly applies to its brightest and best track-seasoned road cars. The 911 2.7 RS was the first of them, launched in 1972 as a true homologation special. In fact it was so brilliant that they ended up making 1590 instead of the 500 that'd have satisfied the race boffins. If it was loved in its day, it's got a crazed cult following now. The greatest early 911? Very probably. The best useable sports car of all time? Some say…

But Porsche has another internal division that also makes hotted-up cars in limited series. This is Porsche Exclusive. Once known as the 'special wishes' department, it gradually began its own production runs, such as the 930 Slantnose. This 964 Turbo S is another of the Exclusive cars; they made just 86 in all.

If you like what you see here, and you're rich beyond avarice, either or both these 911s could be yours. They're both up for grabs in Silverstone Auctions' sale at the Salon Privé at Blenheim Palace on 4 September.

Back in 1972, the 2.7 RS counted as a wide-body. The front rear arches were plumped out, as this was the first 911 with wider back tyres than front. The engine, with the complex and expensive mechanical injection, grew from 2.4 before to 2.7 for the RS. Those things soon spread to other 911s, but the rest of the RS recipe made it uniquely special.

The aero work is obvious. A pure 911 shape is basically one big lift-generating wing. Not good when you want to keep stable at speed. So the RS got a front air dam. And that gorgeous and utterly distinctive calling card, the ducktail spoiler.

The suspension was mostly as per the already sporty 911S, but stiffened and firmed in dampers and bushes. The overall weight tumbled. Parts of the steel and glazing were thinner, and the interior was stripped out. All familiar Porsche work nowadays: lower equipment, higher price. But actually most of the cars sold, including this one, had much of the trim put back in, to make 'Touring' spec. Still, with 210bhp to tickle it along, it's well under 1100kg.

Not just light but tiny. You drop into the soft but cradling tartan seats and the packaging seems miraculous. The cabin has plenty of stretching room in front and two handy seats behind, plus almost uninterrupted outward visibility in every direction. Yet you look along the hills and valley of the front wings and bonnet and realise it's as narrow as a modern minicar.

Which makes it ideal for threading down B-roads. It's not raw performance that matters in the RS. It's the super-fidelity of the connection between your senses and its mechanisms, the instant ebb and flow of information in both directions.

Head off down the road, even down a straight road, and the wheel absolutely dances in your hands. No point in fighting it, for the car's front end bobs and weaves a little, but doesn't fly far of course. It's just sniffing out the moment when you really want to turn.

When you do, it zips into the bend, and the extra tyre load pulses back to your nerve endings through the steering. Use more power (it's available instantly from the ultra-keen engine) and the RS settles and grips. Then you feel the steering wheel ease again, as the tyres begin to gradually surrender their hold. Every surface change, every white line, you feel them all and the effect they have on the grip.

It's not understeering, it's not oversteering, it's just settled and happy. Squeeze the power on exit and it squats a little and shoots forward, again intimately telegraphing the change in front-tyre weighting. People who tested them on tracks when new said they were prone to sharpish oversteering on lift-off in the wet. I've got hedges either side and it's dry and I'm conscious of the value. I let it stay tidy, and I love it.

Sure the ride is a bit less fluent than I expected, but this car hasn't had much use those past decades and could probably do with re-bushing. By the same token when I put some new petrol in the tank the engine soon cleared its throat.

Oh man the engine! It's so happy and chattery and eager, solid in the mid-revs and magically urgent all the way to a 7,200rpm red-line. It fills the cabin and your thoughts and memories. It's everything you've been told about those air-cooled flat-sixes, brimming with charisma yet entirely at your service.

After it's sold no doubt it'll be laid down like cellared bordeaux. That's the wrong destiny. It really could – should – be used all the time. It's not an old clunker: the brakes work as well as a modern hot-hatch's (no ABS, mind), the gearshift isn't heavy (though no match for the precision of a Cayman's), you've got a fifth speed for the motorway and it doesn't even kick up much tyre noise when you subside into a cruise.

Greatest-ever everyday sports car? They may have a point. But now for something for more, shall we say, specialised tastes. The mighty Turbo S.

I remember driving the standard 964 Turbo back when they were new. The Turbo S is broadly the same in texture, but a whole other level of intensity. It's just as different from the regular 964 Turbo as the 2.7 RS was to the contemporary 911S. And there's a far, far bigger gap from 964 Turbo to S than from today's 991 Turbo to S.

For a start, the engine got a right jolt, adding nearly 20 percent to the Turbo's 320bhp, thanks to higher boost, polished ports and different cam timing. Small wonder it needed those gulping air intakes by the rear wheels.

The rear wheels have to cope alone with the resulting 381bhp and 361lb ft. OK they're not scary-high figures by today's standards, but as we'll see this engine is no picnic to operate. The chassis set-up, a special by Bilstein, was stiffened, and lowered like a serpent. A front strut brace ties it together. The front sidelights were integrated into the headlights, to make way for ducts to cool the supersized brakes.

And the car's weight was hacked down. The body shares a lot with the RS of its era, with aluminium doors, thin glass and a carbonfibre front bonnet. In 1992, a carbonfibre panel was a seriously foxy item. Inside, the door trims are simple flats and there's no rear seat. The shell was naked of underseal or much soundproofing. Even, among other details, the screenwash bottle was smaller. It means just 1290kg in all, 180kg lower than the standard Turbo of the time. That's why they named it Leichtbau – light build.

So if the RS 2.7 is probably a 5.7-second car to 60mph, the Turbo S is under 4.5.

Like any 964's, the cabin is architecturally the same as all earlier 911s', but it's had the decorators in. The dials have new typefaces, there are more switches and lights, there's climate control. For the S, because its a Porsche Exclusive car, there's leather all over the place. Even the blades of the air vents are wrapped in leather. In this car that leather is black. Other Turbo Ss are red or green or yellow inside. I can only imagine they reflect the aesthetic of an early 1990s' Stuttgart Nite Klub.

It is all about excess. So is the car. The 911 was always about modesty, about doing great things without fuss. This one makes a right royal fuss. Eventually.

At first you wonder what the hype is about. You get out on the road, ease it through second gear, drop it into third at 2,500rpm and floor it. Nothing in particular comes to pass. Just a gentle accumulation of speed. Wait a bit. Nope. Then, ah. Then, woooo-ah.

This really is old-school turbocharging. Somewhere around 4500rpm it arrives to pin you into that hard bucket seat. It takes a hold and hurls you forward, banging into its absurdly low 6500rpm limiter like a head-butt. You shift up, wait again, then it all repeats. The engine, rattly at low revs and churlish in the middle, becomes a force of nature now.

It needs huge concentration on your part. You're either stuck right off boost, or in that window where you can count four elephants before it comes, or you're in its letterbox-narrow crazy zone between 4,500 and 6,500.

But there are other things calling for your concentration too. If on a B-road's bumps and cambers, the 2.7 RS's nose likes to tiptoe left and right, the Turbo S dives to either side like a wild bull.

You're constantly correcting and re-correcting its path. It's a wider car than the yellow one because of those fat rear wheel-arches. It's a much wider one because it's diving left and right all the time. Even under brakes. Or when you get on, or off, the throttle. And this in a straight line. Or at least what you were hoping would be.

Feed it into corners and its steering, though powered, is full of feel in the way that was – until the 991 era – a Porsche signature dish. And what you feel is understeer. To keep the power in check, the basic behaviour, absent provocation, is to nudge gently outward.

On wider, smoother, more open A-roads the turbo S begins to wear its awesomeness more clearly. It flows more neatly between the lines, and you can see far enough ahead to apply for boost in a timely fashion. You still need to follow the working methods it dictates, but it's less onerous and more rewarding in those conditions.

It's properly rapid even by today's standards, and an overload of all five senses. Yup, you can smell the hot oil. And taste the fear.

I can see why you might get hooked. The contrast between what happens when you get it wrong, and when you get it right, is stark. If you're up for a challenge, the Turbo S sends fireworks around your consciousness.

What a day this has been. What a pair of cars. The 2.7 RS is an evident treasure. Your intimate partner, an extension of your nervous system. Not so the Turbo S. That's not about partnership. It simply bends you to its formidable will.

Click on for more pics