German's magazine Sport Auto July issue has the GTR test results and they were able to drive the GTR around the ring at 7:38, 1 second faster than Ferrari F430 Scuderia but slower than Porsche GT2's 7:32.
7:38 is significantly faster than the Porsche Turbo and also the GTR time tested by Porsche's engineer. The engineer was able to drive the GT2 to a time 7:34 (only 2 sec. off the GT2 record) so obviously he is very good so it's strange why his GTR time is so bad. Perhaps he needs more seat time in the GTR.....
Anyways, so far only Nissan's own driver are able to drive the GTR under 7:30, nobody else have come close to that time.