Porsche 911 GT2 RS vs 911 GT3 RS

Is a Motorsport 911 better with or without turbos? Time to find out!

Two or three? I've been asked it many times; not children, though that's a debate Mrs Fortune and I have been having for a long time. Instead it relates to Porsche's current GT cars. The strength of feeling out there to one or the other is like the People's Front of Judea's scorn for the Judean People's Front - only the splitter here's an aero one.

Powered by naturally-aspirated or turbocharged Stuttgart flat sixes, they hail from the same GT department and were developed in parallel, that much is obvious. GT road car boss Andreas Preuninger even admitted on the quiet that perhaps they should have launched the 3 before the 2, but circumstances prevented it.

That they share so much is unsurprising; what does shock, though, is the extent to which they differ. We'll avoid the debate on lap times, as that's a whole different sport, and instead concentrate on how they feel on the road. I've driven both, but until now the opportunity to sample them back-to-back has proved elusive. That all changes today, on the sensational Scottish roads up near Ullapool, on the North Coast 500 route. The bridge in the pics is Kylesku. The roads around there as brilliant as the scenery, and about as far removed as any track as it gets - even the one where these RSs perform so famously.

I'm in the GT3 RS first. Having been around the Isle of Man in this exact car only a few weeks earlier, it feels very familiar. In the middle of the Irish Sea it mesmerised; its abilities catapulted far beyond the already sensational heights of the Gen I GT3 RS, a car I genuinely couldn't conceive Porsche making any better when it launched. It is though. The changes to the Gen II GT3 RS might have initially logged in the 'meh' category on first reading the specification, but the car is less a minor evolutionary leap than it is an entire change of species.

To that end the GT3 RS has a lot to thank its GT2 RS relation for. It rides on suspension that, barring a slight adjustment to the set-up to account for the differing performance delivery and weights, is all but identical. That's ball-jointed throughout, save for one connection that links the rear-wheel steering system. The spring rates are up, the dampers and roll bars significantly wound back. The effect, on both cars is incredible poise, without any significant compromise in ride quality.

That both can cope with the vagaries of UK tarmac is testament to the GT department's decision to take such a route. The resulting wheel and body control is tremendous, allowing each to better exploit their NA or turbocharged take on the obsessively honed flat-six engine, slung out the back behind the same 325/30 ZR21 tyres. The dimensions are the same, too, save for the 3's slightly lengthier shape (although there's only 8mm in it).

Visually they're riotous, as befits their performance goals, both wearing the aero addenda that defines their track-refugee status, with NACA ducted bonnets, huge intakes to cool, vents to depressurise and evacuate spent air, and rumps adorned with wings so vast they'd surely take flight if they were inverted. As similar as they are, it's the differences that really hit home, the GT2 RS's more upright, plough-like front more pugnacious, likewise the rear's lower diffuser, with the massive exhausts situated in contrasting black bodywork, the GT2 RS, shouting, in Preuninger's own words: "I'm the alpha animal."

That's as may be, but with the 2 RS ultimate downforce wasn't such a key development focus; Preuninger admitting that he wanted less drag to enable its ridiculous pace deep into three figures on the Autobahn. That's a subtly different proposition to the GT3 RS; its aero has always been all about downforce, albeit while still trying to minimise drag, which is the enemy to its racing relations.

It's less overt, relatively speaking, the exhausts inboard, situated among painted rather than contrasting bodywork, lacking the forceful visual pugilism that the 2 RS brings, and denied in UK form its most outrageous look (the Weissach pack being unavailable to British buyers). Either way, they both look incredible - unless you're in the Touring camp, of course.

The chances are you know the figures, but in case you need reminding the GT3 RS produces 520hp from its naturally-aspirated 4.0-litre flat-six. The GT2 RS loses 200cc of capacity for a 3.8-litre flat-six, but adds a pair of variable vane turbochargers with a water-injection induction system, allowing it an almighty 700hp. And the performance? Take these as typically Porsche conservative; the 2 RS reaching 62mph in 2.8 seconds, the 3 RS trailing it by 0.4 seconds. The 3 trailing is true everywhere, 99mph arriving in 5.8 seconds and 124mph in 8.3 seconds as it runs to its 211mph maximum. In Germany, only, of course. The 3, meanwhile, takes 6.9 seconds to reach 99mph, and after that we're left guessing, though it will reach 193mph. Plenty quick, particularly when the limit around here is 60.

Yet the GT3 RS is absorbing enough even at legal speeds to deny me the pleasure of the sensational views. No, the richness here is in the drive, the detail, and the way the GT3 RS is able to engage and delight on the roads that meander like rivers around the topography, every turn and twist communicated with such clarity, dealt with with such precision as to wonder why you'd ever want anything more.

The chassis might have been the key in defining the evolutionary leap with this GT3 RS over the Gen I car, but the engine changes are no mere support act. To experience the 4.0-litre's 9,000rpm redline, and specifically the enthusiasm with which the engine responds all the way to it, should be on every PHer's bucket list. Add a transmission that's so fast as to feel like it's hard-wired to your synapses and the combination of the three, in conjunction with the incredible brakes, creates about as absorbing and immersive a driving experience as you could ever wish for.

The GT3 RS's talent seam is so deep, yet even when you're just scratching at the surface it engages, every input rewarded with immediate response, underpinned with detailed control to the end benefit of speed. The GT2 RS, as with its looks, is more overt in its delivery. That's hardly surprising given the more forceful nature of its engine, the way it hauls from low revs has to be experienced to be believed. That it still loves revs, thrives on them even, is wonderful, the 2 RS's 3.8-litre powerplant representing a revolution in turbocharged engines which takes all of the advantages forced induction brings, yet leaves any compromises on a shelf marked 'history' back in Weissach.

It's difficult not to be seduced by the GT2 RS's massive urge, yet the old adage that power corrupts just isn't applicable. The chassis is more than a measure for the incredible forces that the engine creates. That we've reached a point where an arse-engined, RWD, 700hp turbocharged Porsche can genuinely be described as exploitable underlines just how far we've come. Less widowmaker these days, then, and more mistress - you'd spend less and less time at home if you had one of these...

Here, on these roads, its ability to shorten journey times is other-worldly, arriving at the next corner seemingly before you've exited the last one. It's that fast, for which you can read, that capable. There's the same incredible poise, the chassis acting as an enabler to the phenomenal engine; ably assisted by the brakes' unerring stopping power and the PDK transmission's ability to fire up and down its seven ratios with impunity.

What is surprising over the same roads is how different they feel. Yes, the anticipation is of nuances, but had you described this experience I'd have dismissed it. The GT2 RS feels bigger, physically, a manifestation of its greater performance potential, even if the reality is that they occupy the same amount of tarmac. It's not a blunt tool by any measure, but the rear axle's dominance is apparent, the steering marginally less eager to turn in than on the GT3 RS.

Where the GT2 RS delivers more of its performance earlier, the GT3 RS needs teasing to produce its best. There's a greater input to reward ratio with the 3, simply because you have to work it that little bit harder to deliver. That the reward is a 9,000rpm redline is enticing enough, the sound emanating from it as it reaches those heights being of the goosebump-inducing variety. The GT2 RS's mightier, deeper notes are sensational, but lack the finer delicacy of the 3's tunefulness.

Both are incredible, intoxicating cars, and for me to say one is better than the other is nigh on impossible, if not arguably moot given many buyers will simply have both. But I'll stick my head out there, disagreeing with the man responsible for building them himself, and say if I had to pick one it would be the GT3 RS. To many, that'll be wrong, to others right. I don't really care, as both factions have enormous merit. What is indisputable, however, is that both camps having such outrageously talented, exploitable and engaging offerings available to them is surely no bad thing.

SPECIFICATION - PORSCHE 911 GT3 RS

Engine: 3,996cc flat-six, petrol
Transmission: 7-speed PDK, rear-wheel drive
Power (hp): 520@8,250rpm
Torque (lb ft): 347@6,000rpm
0-62mph: 3.2sec
Top speed: 194mph
Weight: 1,430kg (DIN)
MPG: 22.1
CO2: 291g/km
Price: £141,346

SPECIFICATION - PORSCHE 911 GT2 RS

Engine: 3,800cc twin-turbocharged flat-six
Transmission: 7-speed PDK, rear-wheel drive
Power (hp): 700@7,000rpm
Torque (lb ft): 553@2,500-4,500rpm
0-62mph: 2.8secs
Top speed: 211mph
Weight: 1,470kg (DIN)
MPG: 24
CO2: 269g/km
Price: £207,506 (plus £21,042 for Weissach package)