Disagree somewhat on both parts.
I think alot of people dont relize, That effort and time it takes to get that kind of result, alot of people are ONLY taking into account that single laptime, That 7:08, Take a pro driver, WHo knows the track like the back of his arse, Knows the car inside and out, Day by day night by night, Lowest liquid loads, Maximum performance options, Best conditions, Hundreds upon hundreds of attempts, And Bam!, You get a 7:08, If every company did that, We would see ALOT of time shaven from every car.
The reason why non if the Nismo other track times dont look as good, Is the exact opposite of what i just listed in order to get the 7:08 time, The video proved it, May not be "Absolute" proof, But we cant prove them wrong.
Also, The Viper did that 7:12 in 5 laps, With non of what Nissan had, And that is seriously impresive, And given if they had that, You can expect alot more time to come ut of it. Same with every car.