There’s something very puzzling about Nissan’s all-new GT-R supercar. Its official output figures read 480hp (358kW) and 588Nm (434lb-ft) of torque and its mass registers at 1,723kg, but the car can still outrun the 911 Turbo around the notorious Nurburgring by a healthy margin despite the Porsche weighing less and producing more torque (1633kg and 457lb-ft respectively).

Nissan’s official lap time for the Nurburgring is a blistering 7m 29s, set back in May. The lap times were for a stock-standard base specification GT-R fitted with the same Japanese market tires as the cars in showrooms, according to claims by Nissan.

Porsche, however, claims Nissan falsified these numbers and posted the quicker times because of semi-slick race-style tires. The German sports carmaker even purchased its own GT-R and set about testing it against both the 911 Turbo and GT2 and in both cases it claims the GT-R was the slowest. The laps were run by one of Porsche’s chassis development engineers and not its regular tester, former world rally champion and race winner Walter Rohrl.

Speaking with Australia’s CarsGuide this week, Porsche’s 911 product chief August Achleitner said the GT-R used by Nissan to post its official times could not have been a regular series production car.

He said Porsche took a standard GT-R bought in the United States and running on regular road tires, and was tested on the same day as the pair of 911s. According to Porsche, the GT-R posted a time of 7m 54s, with the 911 Turbo managing 7m 38s and the GT2 getting down to 7m 34s.