Facing off against the Porsche 911 has rarely been a productive use of car manufacturer resources.
In fact, most rival car makers have looked at Porsche's flagship and come to an uneasy accommodation, namely that they're clever enough to avoid tackling it head-on, but not so smart that they've figured out how to build a better sports car themselves.
Therefore, it comes as quite some surprise to discover that Mercedes-AMG have painted a big roundel on the back of the Porsche 911 GT2 RS and taken aim.
Its new GT Black Series is, like Porsche's powerhouse, a lighter, stiffer, angrier proposition than the rest of the range, so let's see how it squares up in a few vital areas.
NURBURGRING LAP TIME
The Porsche 911 GT2 RS has form here. It scorched to an almost unbelievable lap of 6:47.3 in 2017 with Lars Kern at the wheel, before the same driver lowered that mark with a 6:40.3 time in the factory-sanctioned GT2 RS MR model. That time is a mere second off what then-F1 world champion Keke Rosberg achieved in a factory 956 during qualifying for the 1983 Nurburgring 1000km.
That's a jaw-dropping time for a car wearing number plates and fitted with airbags and road-legal tyres.
By contrast, we've heard strictly unofficial whispers that the GT Black Series has logged a 6:58 lap of the Green Hell, which is 6.6 seconds quicker than the AMG GT R Pro model, but still a little off the Porsche's demented pace.
Again, we'd reiterate that this isn't an official AMG time and that Affalterbach might well be considering another crack in better conditions.
Verdict: Porsche, until we hear otherwise
The most powerful road-going Porsche was fitted with a 3.8-litre twin-turbocharged flat-six capable of 515kW at 7000rpm and 750Nm anywhere between 2200 and 4500rpm. That's a specific power figure of 135.5kW per litre.
By contrast, the heavily revised flat-plane V8 of the GT Black Series ladles out a massive 537kW between 6700 and 6900rpm and peak torque of 800Nm in a broad swathe between 2000 and 6000rpm. Specific power? A near-identical 134.9kW/litre.
Both deploy torque to the rear treads via a dual-clutch seven-speed transmission, so there's not going to be a lot of variation there, the AMG using a 13.9kg carbon fibre torque tube. The Porsche doesn't need one of these for obvious reasons.
Verdict: AMG by a nose
STRAIGHT LINE SPEED
AMG is quoting a 0-100km/h time of 3.2 seconds and a top end of 325km/h, and also states that the GT Black Series will accelerate to 200km/h in less than nine seconds.
That's an extremely quick car. Weighing 1540kg, the Black emerges with a power-to-weight ratio of 348.7kW/tonne.
We're fairly certain that a front-engine car won't get the drop on a GT2 RS out of the blocks though.
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The Widowmaker logs a 2.8 second time to 100km/h and 8.3 seconds to 200km/h, with a top speed of 340km/h.
The 911 GT2 RS tips the scales at 1470kg, which sees AMG's power advantage cancelled out and Porsche realising a small advantage here with 350.3kW/tonne.
Verdict: Porsche victory
AMG has clearly channelled a lot of its GT3 and GT4 racing experience into the aerodynamics of the GT Black Series.
Its most obvious feature is the vast rear wing. This features an active element which can either be manually controlled via a switch on the dash or left to its own devices to act according to which of the Basic, Advanced, Pro or Master drive modes the car is set into.
At speeds of over 250km/h this wing flap retracts, but will pop back up to add stability under hard braking or steering.
The underbody of the AMG is also virtually flat, with longitudinal fins guiding air to a functional rear diffuser. AMG claims a downforce level of well over 400kg at 250km/h. The grille has been modified with the central inlet now ducting air to the engine and the brakes. Where the outer inlets were, there are now guiding flics to increase frontal downforce.
Like the AMG, the Porsche also employs a carbon roof to lower its centre of gravity, but this is part of the optional Weissach package. The intakes in the Porsche bonnet channel air to the brakes while the vents in the AMG's bonnet suck hot air out over the exhaust manifold.
The GT2 RS generates 340kg of downforce at full 340km/h speed, so the AMG is generating more aerodynamic downforce at a lower speed. Clearly this doesn't come for free, and the combination of a lower top speed and higher torque and power figures suggest the GT Black Series is a draggier car.
Verdict: AMG wins the downforce battle
TYRE AND SUSPENSION
As in F1, GT Black Series drivers get a choice of tyre compounds. The Michelin Pilot Sport Cup 2 R MO tyre is available in soft (M01A compound) or an optional hard (wearing an M02 designation) better suited for high temperature track use. The front tyres are 285/35 ZR19 with the rears measuring a massive 335/30 ZR20.
Go Porsche and the rubber measures 265/35 ZR20 up front and 325/30 ZR21, so a different strategy: slightly narrower tyres on wheels that are an inch bigger front and rear.
We like the Michelin Pilot Sport Cup 2 tyres on the 911, but some swear by the Goodyear Eagle F1 Supersport RS rubber that Porsche also supplies in some markets. Both cars reduce unsprung weight with carbon ceramic stoppers.
The Porsche's strut front suspension and multilink rear contrasts with the double A-arms all round with adaptive dampers on the GT.
The AMG also features a carbon front anti-roll bar, manually adjustable camber on both front and rear axles and no-play spherical bearings on the upper and lower wishbones of the rear axle.
Which is more effective in the real world? That's going to take a full road test to discover.
Verdict: Jury's still out here
Be very aware of the fact that any car that is capable of running a full lap of the ‘Ring in less than seven minutes is likely to be way more car than you or I are capable of exploiting to the full.
What laypeople will be able to appreciate is that the Porsche will be marginally more savage away from a standing start or that the Mercedes is generating considerably more downforce to stick it to the road or track surface.
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Which wins? Well, of our five categories, it's two wins each and a draw for the other, so we're not able to split the two cars just yet.
Timing may well render this one moot in any case. By the time the AMG GT Black Series arrives in our hands, the 991 generation of GT2 RS will have been sold out.
So, in that regard at the very least, it'll be a victory by default for Affalterbach but given the development budget ploughed into the Black Series, we don't think they'd mind if we lined up a sneaky back-to-back at some point in the future.