Both the Corvette and Viper have been plagued by bad luck in getting their Nurburgring times.
To sum up the Viper, they got ZERO factory support. Kumho supported them with tires, but they were than desired. They ran the car so hard one lap became one set of tires. It was a bunch of freelance dudes with Vipers, and their final time was 7:01.
Here’s an article from Jim Mero on the bad luck of the Corvette. They had no official time.