ZR1X lap 6:49.275 (barely beating the GT3 RS, I’m sure the MR will beat this time soon) http://www.youtube.com/watch?v=ic7qpuJtHK4
ZR1 lap 6:50.763 http://www.youtube.com/watch?v=20oDQHBrWSA
Z06 lap 7:11.826 http://www.youtube.com/watch?v=u1yh7Ptrhwo
They used the American spec Z06 not the slower European one (emissions?).
According to Chevrolet, the Corvettes that performed at the Nürburgring were all U.S. production-spec vehicles with the only modifications being the safety equipment recommended by track officials. This includes a roll hoop, full containment race seats, fire extinguisher, and a six-point safety harness. All three vehicles set lap times for the Prototype/Pre-Production category since the ZR1 and ZR1X are not sold in Europe, and the Z06 was a North American variant.
This just sounds like an attempt to deflect criticism. “Oh I wasn’t really trying”, either put up or shut up. These are their times and they will continue to be until someone beats those times with stock cars.
Also the drivers are actually good, so it’s a bit misleading to paint them as amateurs.