GT-R Nurburgring lap time discrepancy explained

When Porsche bought a Nissan GT-R two years ago and failed to match the lap time set by Nissan's top test pilot on the famous Nurburgring race circuit in Germany, there were veiled accusations of cheating.

At the time, the head of the development at Porsche, August Achleitner, said: "This wonder car with 7:29 could not have been a regular series production car."

To prove that the sub 7 minute 30-second time was possible, Nissan beat its original record set in April 2008 one year later, in April 2009, with a time of 7 minutes and 26.7 seconds. Porsche then went silent on the subject.

But the two-year-old mystery may finally be solved -- and it comes down to what tyres the rivals were using. In an exclusive interview with the Carsales Network at Australia's Phillip Island Grand Prix circuit, the chief test driver for the Nissan GT-R, Toshio Suzuki, believes Porsche used the wrong tyres.

The Nissan GT-R is available with a choice of two tyres. The regular model comes with Dunlop SP600 tyres but the luxury version comes with Bridgestone RE070 tyres, which have a race-like semi-slick tread pattern. Porsche is understood to have used the Bridgestone tyres on its GT-R test in the belief that the semi-slick treaded tyre would be quicker. In fact, the regular-looking Dunlop is the quicker of the two available tyres.

"Around the Nurburgring, the Dunlop is about 4 to 5 seconds a lap faster than the Bridgestone," Suzuki-san told the Carsales Network. "For track driving, we always recommend this tyre but not everybody knows this."

Indeed, all the cars used to demonstrate the new model for 2010 were equipped with Dunlop rubber. The Bridgestones were removed and left in the pit bay.

When Suzuki-san was asked if this is the reason for the discrepancy in the Porsche time, he shrugged his shoulders, smiled and said: "I cannot comment about that test, but we think maybe they use the wrong tyre."

Porsche guessed this may have been the case at the time, but they damaged the gearbox on their GT-R and had to cut their test short before being able to try the other rubber. In his original interview, Porsche's Achleitner said: "For us, it's not clear how this time is possible. What we can imagine with this Nissan is they used other tyres."

As Nissan prepares to launch the updated model for 2010 (now with navigation, wireless Bluetooth phone connection, revised suspension and more power and torque down low but the same peak outputs as before), Suzuki-san is heading to the Nurburgring to test some minor updates for the 2011 model.

"But on this occasion we will not attempt to better our current time," he said. "We will wait until autumn and try to beat our current record in September or October 2010 when the temperature is better."

He said there were more developments with the engine and suspension, plus a new tyre option.

"You will have to wait and see but we think we can be quicker still," he said.

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