There was a thread about this a while ago... Some guy who clearly couldn't find a racing line even if it slapped him in the face... He was claiming his 6.42.xxx was a world record, then started acting like a spoiled kid when he realised it wasn't. Determined to beat him, I lapped a 6:35.xxx but some other gtplanet user managed a 6:30.xxx and uploaded a video to prove it.
After seeing his video, and taking exception to his tone, I actually bought said car just to prove a point, but another user managed to do better, so I thought I would just leave things as they were.
I'm using a DS3. Could've done better than 6.35.xxx but doubt I could get 6.30.xxx.