I would not question the claimed 6.7s at all, and I believe it. However, it's a matter of consistency. Out of 10 0-100 runs I'd say there might be 1-2 under 7s runs. So conclusion is it's achievable, but not easy and a tad optimistic. Whereas if you drive like a golf gti, lot's of people can do better than the claimed 7.2s without much effort.