| First Drive | Herts, England | Porsche 911 GT3 RS |

Forget about the £14,000 premium this car costs over the regular 911 GT3. This is an RS, and no two letters signify more in Porsche-dom than that evocative pairing. Since the 996 RS those two small, but so significant letters, have been tagged alongside the GT3 badge. But that marriage of letters and numbers promises so much. After all, what better model to base its most extreme lightweight racer for the road than, err, an extreme lightweight racer for the road?

Forget too that the weight difference between the 'ordinary' GT3 and the GT3 RS is only around 20kg. That's hardly the 100kg or so of weight reduction Ferrari managed with its 430 Scuderia, but then the GT3 represents a tougher, already lightened starting point. The GT3 RS has more than merely shed kilos; it's a bit more involved than that. Not that you'd know from the numbers; there's really not much in it between the GT3 and the RS either - we're talking about fractions of a second to 62mph. Indeed, if the RS was lined up alongside a regular GT3 for a V-max run it's the cheaper car that would record the higher speed.

You'll also need to be a proper Porsche nut to spot the difference in looks. At least you would if Porsche didn't sticker up the RS with script down its flanks and paint the wheels to ape its iconic '73 ancestor. Porsche will leave off the decals if you ask nicely, and we're sure you could have the alloys without the contrasting paint, but why would you? It's an RS and it should look like one.

Where it does differ is rather than being based on the slim-hipped Carrera 2, the RS's DNA has traces of Carrera 4. That means a slight increase in the width at the rear, not so much to be hugely obvious, but enough. It also means the RS benefits from all the additional stiffening at the front for the Carrera 4's four-wheel drive hardware. It's these small differences that make the RS so special. Some of the others include different suspension arms, revised hub carriers, slightly altered gearing and a wider track. The engine features a single-mass, lighter flywheel to enable it to gain revs more rapidly, too.

And what an engine it is. More than merely a tweaked example of one of the Carrera's lumps, the GT3 RS's engine is an exotic race-derived unit. Its roots go back to Porsche's 911 GT1 race car and from its 3.6 litres it produces 415bhp. That peak power is developed at a heady 7,800rpm, but it's not the recalcitrant, peaky engine you might expect, being surprisingly happy to crawl along at low revs in traffic. Ample torque is key to its civility - 332lb.ft being delivered at 5,500rpm - and a good chunk of that is available from just above idle. Firing it up and its race pedigree is clear, the tappety metallic clattering from behind initially sounding like an engine that's about to lunch on its own internals.

But before you get the chance to scare yourself starting the RS a few gymnastics are required. The GT3 RS isn't a car you simply get in and twist the key. At least it's not if you're anything less than featherweight yourself. The deep sports seats require shuffling into, the seatbelt's anchor rarely easily located once you're in. Easing entry by pushing the seat as far back as possible also means you'll spend a few moments re-setting your driving position.

That's no bad thing, as the RS is about savouring the moment. It's about maximising the driving pleasure, enjoying a pure adrenaline shot of 911. So the song-and-dance required behind the wheel is a fitting precursor to what's ahead. Yet, the first thing that strikes you is how friendly it is. There's some chuntering from the tight diff at the rear if manoeuvring out of a tight spot and the gearshift is a bit reluctant until its oil has warmed up. The steering initially feels weighty too, but the promise of unrivalled feel is a small price to pay for some slow-speed heft.

Once everything's warmed though it's time to discover just what that engine is capable of. It feels little quicker than the GT3, 62mph arriving in 4.2 seconds rather than 4.3, but that lightened flywheel means the engine revs with more vigour. The throttle response is instantaneous and exact, its high-rev performance staggeringly urgent and demanding quick changes with the beautiful mechanical shift action of the six-speed manual.

The steering is super quick and the front goes exactly where you want it. What the rear then does is entirely up to you, if you're skilful and prepared to switch off the electronics there's power oversteer on demand, the GT3 RS a remarkably easy car to steer under power. Keep it tidy and it's wickedly precise, the RS is a demonstration of accuracy, feeling hard-wired to your input. Fitted with PASM (Porsche Active Suspension Management) for the first time there's no point in opting for the stiffer setting on the road. Press the Sport button though, for the full-on RS experience, the limits of the electronic thresholds are raised and a cheeky flap opens in the exhaust to free up the breathing and harden up the soundtrack even further.

It's an intense experience and a demanding one; the acceleration, braking - which seems limitless with the optional carbon ceramic PCCB brakes - and G-forces involved making the RS a very visceral and busy car to drive. It's unlikely that you'll ever tire of the noise it makes, the purposeful flat-six sound turned up to 11 with a harder edged menace added for good measure. The GT3 RS is a special car, admittedly a bit raw for some, but if you like your 911s with a bit more edge then the RS is unsurpassed.