So, this is the endgame limited-edition run-out special of the 997-series Porsche 911. And like a lot of run-out specials, it has a spoilers and stripes. And while they might be the maddest spoilers and the stripiest stripes you ever did set eyes upon, they aren't the point. Instead it's all about the engine.

This is definitely, positively, the last road-going appearance for the Mezger flat-six, so-called because it was the culmination of the brilliant career of Hans Mezger, one of Porsche's lynchpin engineers for four decades up to the mid-Nineties (the 917, the TAG McLaren F1 engine, dot dot dot). This crank and block won Le Mans in 1998, mid-mounted and turbocharged in the Porsche GT1 car. This is an engine with heritage, character and immense physical integrity.



And to mark its departure, they've stretched it from 3.8 to four litres, so we end up with a 500bhp, normally aspirated flat-six. In a car that weighs 1,360kg with all fluids aboard. It's £128,466, and it's sold out.

I'm being told, by the engineer behind Porsche's GT cars, Andreas Preuninger, just how much effort and complication this involved. I could listen to him all afternoon, for two reasons.
One, it's fascinating. Two, the car is right outside, awaiting my pleasure around Silverstone. And while part of me, obviously, is busting to jump in and see how very awesome 500bhp feels in a GT3, a very significant other part of me is repeatedly postponing the moment.



I am not a racing driver, and the GT3 RS - with its Sabatier wings and steamroller tyres and air of dismissive snort - looks like it will make a berk of me, or worse. On early laps, the racing 'box - with shorter, stiffer throws then a normal 911's - finds me uncalibrated, and I keep overshooting the gate.

The clutch is sharp, the steering darty, the carbon brakes so ridiculously powerful I either arrive at the corners way too slowly or outbrake myself on the crest. And anyway, the speeds at the ends of the straights are surreal because of all that power. Car is way too good for bloke. But instead of losing interest, car gently coaches bloke.



The engine might have 125bhp per litre, but miraculously it also has a big wide cushion of powerband, so I begin shifting gears in moments when my head clears. The quick, safe-bolt gearlever action rewards like no semi-auto ever can.

But it's the handling that's the revelation. The already super-focused GT3 RS chassis has been given slightly firmer springs, but also a change from conventional rubber to racing solid ball joints for all the lower joints at the rear. It brings a new increment of precision.



There's something else too, a trick option from the 2009 GT3. ‘Active Drivetrain Mounts' stay soft for refinement in normal driving and gearshifting, but pretty well lock the engine and 'box to the body when you're pressing on, keeping its weight fixed in place. Good: the big dog in the boot is now harnessed down rather than scrabbling around.

It all means extraordinary connection. The suspension, so free of slack, keeps you intimate with the tyres, and the steering feel is just as good as the world's 911 cheerleaders have always advertised. What's new here though is that it's not just that every input from you gets an output from the car, but that as soon as you cease the input, the output ceases too. So it's magically prompt and progressive in reflecting your acts and the changes in the surface underneath.



Too much braking into a sharp corner? Understeer. Nose going over a little crest? Steering goes light as the front tyres unload. Settled and power on? Beginnings of oversteer. Unsettled and power-off? Ditto. Always with the option to fix it by adjusting the astoundingly progressive delivery. And then, in fast corners taken properly, the car pressed down by its aero and devouring roadway like it hasn't eaten in weeks.



The 4.0's tail stays rail-precise, right to the moment where it clearly telegraphs the surrender of grip. And throughout, whether on road or track, the stability control is supernatural. So it's fine as a road car. It's fine as an everyday road car actually, except you might think about ear plugs for the motorway to fend off the crazy tyre noise (solid joints, eh?). And the heavy race clutch turns traffic into harder legwork than cycling. Otherwise, no issues. You need a certain swagger to sit with that tail spoiler, mind. Don't know if I do.

Still, at least it has a nice coat of paint. They could have left it sinister naked carbon - the front wings and bonnet too, for that's what they are. Doors are aluminium, rear-side windows Perspex, aircon and nav no-cost options. But that's all GT3 RS 3.8 stuff.



Even the rear wing is the same, though angled steeper for even more downforce - so much so that it levers the front end upwards, for which those little front sideburns compensate. But the real new sorcery is the engine. Regular Carreras have had a different engine family for years, and the phase II 997 Turbo switched to that new family too, all with direct injection. So the Mezger was left to drive the GT3 and turbo GT2, and their RS and racing relatives. Porsche can't bear the cost of continuing with both, so this is it for the old soldier.

It isn't a pure race engine; those don't have variable cam-timing or inlet geometry because they don't have to be driven between rush-hour traffic lights without stalling or poisoning the pedestrians. But the crank and block in the new GT3 RS 4.0 are exactly as last year's racing GT3 R 4.0. It's a longer stroke than the 3.8, because there wasn't room to widen the bore.



Yet even so, the new RS 4.0 isn't just a long-stroke version of the 3.8 RS road engine. The heads, the intake manifold, the exhaust, the valve-timing, they're all new, to get the best balance of revs and torque and power. Open the lid, and you see a honking pair of conical race-type air filters in a carbon box.

And for that you get an engine that's hugely muscular but alert too. It hums and roars and howls at 8500rpm, kicking your head back with the physical force and its own emotional enthusiasm. It buzzes with simple joy. In its death year, it is more alive than ever. The end of the 997 isn't some slow fading descent into darkness, but a brilliant, blinding flash.