Clearly the car is fast as hell. I just have a really hard time believing a time like this was achieved with OOB equipment and setup.
The AMG is a 1.550 kg REAR wheel drive, front engine car with partly carbon fiber chassis and 585 PS.
Yet it somehow beats a mid-engined, 4WD two-seater 1.640 kg full-carbon chassis car with 887 PS.
Not only that, it also does it despite having a top speed of 320 km/h versus the 918´s 350 km/h.
On top of that, they did it using street legal, production car rubber.  

Commenting on their Youtube video, Auto Sport stated that the rubber only has to have 1.6 mm grooves to be street legal, which seems to be a very odd comment to make, if you´re testing a car that is supposedly the same as the one customers will get (fresh tires, one would assume). 
I mean, why even open a debate about groove depth if the tires are NOT so groove-less they border on slicks, or ARE slicks? 

Also, why do they seem to have slicks for the car lined up? (See picture. Not my comment fyi.)
They just happened to be there? They are worn Michelin Pilot Sport Cup 2? 
If they are slicks, why are they even there? Perhaps there is a perfectly logical explanation?

Sport Auto cleared the front page with "faster than the 918 Spyder", which makes me wonder if they are more interested in selling magazines (or promoting this car), than making accurate statements. 
As we all know, the 918 driven by Marc Lieb was 14 seconds faster, yet they choose to compare the time to their OWN 918 time. It´s like me stating that I just outran a 918 in my RS3 (...because I drove the 918 slowly)cheeky

"They wouldn´t risk cheating, and why would they?"
This seems to be an airtight argument. One that I would agree with - if it wasn´t for the many proofs to the contrary.
It wouldn´t be the first time someone bent the truth or rules to promote a car, or any other product.
People and companies lie all the time to get ahead, sell magazines or whatever their goal is. 

How about Diesel-gate?
Or remember the The Ferrari/McLaren spying scandal of 2007? Or the illegal launch control systems of Benetton?
The BAR hidden fuel tank, the secret McLaren automatic gearbox program, or Ferrari´s traction control in 1995?
Wherever there is big money involved, corners will be cut.
Besides, who can prove what tires Sport Auto were using, or if the PS Cup 2 were street legal or not?

Unless the AMG 9-level TC system, the active rear axel and their aerodynamics package is SO groundbreaking, never-seen-before (and amazing), that it compensates for other clear shortcomings compared to the 918, I don´t believe this time was set with a production spec car. Not even close.
My guess is they simply wanted and/or needed the PR, and cut a few corners to get there. 
I may be wrong, and in that case I can´t wait to see how this amazing new technology will change the game when it´s passed down to other cars in the future. 
Like some have already stated: we´ll see when a third party tests an actual client-ready GT-R.

IRL it doesn´t make one bit of difference to anyone buying an AMG GT (R or any other version).
It´s still an awesome car, and to the lucky few it will still be an amazing ride I am sure.
Which makes these "production car" tests seem like an even more moot idea in the first place.
 
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